Plugins

Hermes has a plugin system for adding custom tools, hooks, and integrations without modifying core code.

If you want to create a custom tool for yourself, your team, or one project, this is usually the right path. The developer guide's Adding Tools page is for built-in Hermes core tools that live in tools/ and toolsets.py.

→ Build a Hermes Plugin — step-by-step guide with a complete working example.

Quick overview

Drop a directory into ~/.hermes/plugins/ with a plugin.yaml and Python code:

~/.hermes/plugins/my-plugin/
├── plugin.yaml      # manifest
├── __init__.py      # register() — wires schemas to handlers
├── schemas.py       # tool schemas (what the LLM sees)
└── tools.py         # tool handlers (what runs when called)

Start Hermes — your tools appear alongside built-in tools. The model can call them immediately.

Minimal working example

Here is a complete plugin that adds a hello_world tool and logs every tool call via a hook.

~/.hermes/plugins/hello-world/plugin.yaml

yaml

name: hello-world
version: "1.0"
description: A minimal example plugin

~/.hermes/plugins/hello-world/__init__.py

python

"""Minimal Hermes plugin — registers a tool and a hook."""

import json


def register(ctx):
    # --- Tool: hello_world ---
    schema = {
        "name": "hello_world",
        "description": "Returns a friendly greeting for the given name.",
        "parameters": {
            "type": "object",
            "properties": {
                "name": {
                    "type": "string",
                    "description": "Name to greet",
                }
            },
            "required": ["name"],
        },
    }

    def handle_hello(params, **kwargs):
        del kwargs
        name = params.get("name", "World")
        return json.dumps({"success": True, "greeting": f"Hello, {name}!"})

    ctx.register_tool(
        name="hello_world",
        toolset="hello_world",
        schema=schema,
        handler=handle_hello,
    )

    # --- Hook: log every tool call ---
    def on_tool_call(tool_name, params, result):
        print(f"[hello-world] tool called: {tool_name}")

    ctx.register_hook("post_tool_call", on_tool_call)

Drop both files into ~/.hermes/plugins/hello-world/, restart Hermes, and the model can immediately call hello_world. The hook prints a log line after every tool invocation.

The model-facing tool description belongs in schema["description"]. The optional ctx.register_tool(description=...) value is separate ToolEntry registry metadata: when omitted, it defaults to the schema description, but Hermes does not copy it back into a schema that lacks description. Prefer defining the text once in the schema. If you provide both values, keep them synchronized; the model sees the schema value.

Project-local plugins under ./.hermes/plugins/ are disabled by default. Enable them only for trusted repositories by setting HERMES_ENABLE_PROJECT_PLUGINS=true before starting Hermes.

What plugins can do

Every ctx.* API below is available inside a plugin's register(ctx) function.

Capability	How
Add tools	`ctx.register_tool(name=..., toolset=..., schema=..., handler=...)`
Add hooks	`ctx.register_hook("post_tool_call", callback)`
Add slash commands	`ctx.register_command(name, handler, description)` — adds `/name` in CLI and gateway sessions
Dispatch tools from commands	`ctx.dispatch_tool(name, args)` — invokes a registered tool with parent-agent context auto-wired
Add CLI commands	`ctx.register_cli_command(name, help, setup_fn, handler_fn)` — adds `hermes <plugin> <subcommand>`
Inject messages	`ctx.inject_message(content, role="user", session_key=...)` - see Injecting Messages
Ship data files	`Path(__file__).parent / "data" / "file.yaml"`
Bundle skills	`ctx.register_skill(name, path)` — namespaced as `plugin:skill`, loaded via `skill_view("plugin:skill")`
Gate on env vars	`requires_env: [API_KEY]` in plugin.yaml — prompted during `hermes plugins install`
Distribute via pip	`[project.entry-points."hermes_agent.plugins"]`
Register a gateway platform (Discord, Telegram, IRC, …)	`ctx.register_platform(name, label, adapter_factory, check_fn, ...)` — see Adding Platform Adapters
Register an image-generation backend	`ctx.register_image_gen_provider(provider)` — see Image Generation Provider Plugins
Register a video-generation backend	`ctx.register_video_gen_provider(provider)` — see Video Generation Provider Plugins
Register a context-compression engine	`ctx.register_context_engine(engine)` — see Context Engine Plugins
Register a terminal execution backend (cloud sandbox)	`ctx.register_terminal_environment_provider(provider)` — see Terminal Environment Plugins
Route human approval prompts	`ctx.register_approval_transport(name, present_fn)` — see Approval transports
Register a memory backend	Subclass `MemoryProvider` in `plugins/memory/<name>/__init__.py` — see Memory Provider Plugins (uses a separate discovery system)
Run a host-owned LLM call	`ctx.llm.complete(...)` / `ctx.llm.complete_structured(...)` — borrow the user's active model + auth for a one-shot completion with optional JSON schema validation. See Plugin LLM Access
Call an MCP tool (capability-gated)	`ctx.call_mcp(server, tool, arguments, timeout=30)` — see Calling MCP servers from plugins
Register an inference backend (LLM provider)	`register_provider(ProviderProfile(...))` in `plugins/model-providers/<name>/__init__.py` — see Model Provider Plugins (uses a separate discovery system)

Plugin discovery

Source	Path	Use case
Bundled	`<repo>/plugins/`	Ships with Hermes — see Built-in Plugins
User	`~/.hermes/plugins/`	Personal plugins
Project	`.hermes/plugins/`	Project-specific plugins (requires `HERMES_ENABLE_PROJECT_PLUGINS=true`)
pip	`hermes_agent.plugins` entry_points	Distributed packages
Nix	`services.hermes-agent.extraPlugins` / `extraPythonPackages`	NixOS declarative installs — see Nix Setup

Later sources override earlier ones on name collision, so a user plugin with the same name as a bundled plugin replaces it.

Plugin sub-categories

Within each source, Hermes also recognizes sub-category directories that route plugins to specialized discovery systems:

Sub-directory	What it holds	Discovery system
`plugins/` (root)	General plugins — tools, hooks, slash commands, CLI commands, bundled skills	`PluginManager` (kind: `standalone` or `backend`)
`plugins/platforms/<name>/`	Gateway channel adapters (`ctx.register_platform()`)	`PluginManager` (kind: `platform`, one level deeper)
`plugins/image_gen/<name>/`	Image-generation backends (`ctx.register_image_gen_provider()`)	`PluginManager` (kind: `backend`, one level deeper)
`plugins/memory/<name>/`	Memory providers (subclass `MemoryProvider`)	Own loader in `plugins/memory/__init__.py` (kind: `exclusive` — one active at a time)
`plugins/context_engine/<name>/`	Context-compression engines (`ctx.register_context_engine()`)	Own loader in `plugins/context_engine/__init__.py` (one active at a time)
`plugins/model-providers/<name>/`	LLM provider profiles (`register_provider(ProviderProfile(...))`)	Own loader in `providers/__init__.py` (lazily scanned on first `get_provider_profile()` call)

User plugins at ~/.hermes/plugins/model-providers/<name>/ override bundled model providers of the same name (last-writer-wins in register_provider()), so you can replace a built-in provider profile without any repo edits. Memory providers resolve the other way round: for ~/.hermes/plugins/memory/<name>/ the bundled provider wins on a name collision (bundled, then user, then project, then entry points; first seen wins), so a user memory provider needs its own unique name.

Plugins are opt-in (with a few exceptions)

General plugins and user-installed backends are disabled by default — discovery finds them (so they show up in hermes plugins and /plugins), but nothing with hooks or tools loads until you add the plugin's name to plugins.enabled in ~/.hermes/config.yaml. This stops third-party code from running without your explicit consent.

yaml

plugins:
  enabled:
    - my-tool-plugin
    - disk-cleanup
  disabled:       # optional deny-list — always wins if a name appears in both
    - noisy-plugin
  # Optional: wall-clock cap (seconds) for timeout-bounded in-process Python
  # plugin hook callbacks (hot-path observers + pre_tool_call). Default 30;
  # set 0 to disable; values above 600 are clamped. Timed-out pre_tool_call
  # callbacks fail closed (block the tool). Caller-thread hooks such as
  # subagent_stop are never moved onto a timeout worker.
  # Shell hooks keep their own per-entry timeout under the top-level hooks: key.
  hook_callback_timeout: 30

Three ways to flip state:

bash

hermes plugins                    # interactive toggle (space to check/uncheck)
hermes plugins enable &lt;name>      # add to allow-list
hermes plugins disable &lt;name>     # remove from allow-list + add to disabled

After hermes plugins install owner/repo, you're asked Enable 'name' now? [y/N] — defaults to no. Skip the prompt for scripted installs with --enable or --no-enable.

For a reproducible install, pin a full immutable commit (tags, branches, and abbreviated SHAs are not accepted):

bash

hermes plugins install owner/repo --ref 0123456789abcdef0123456789abcdef01234567

Hermes checks out the commit detached, verifies that HEAD exactly matches the requested SHA, and records the canonical source, installed revision, and pin status in the current profile. hermes plugins update refuses to move a pinned plugin; choose a new exact commit explicitly with hermes plugins install <source> --force --ref <new-commit>. The profile-local install metadata contains no config values, environment values, secrets, or capability grants.

The same pin is available in Hermes Desktop: Skills → Plugins → Install from Git has a Pin to commit field that takes the full 40-character SHA, and the plugins list shows a pinned @ <sha8> badge on every pinned install so a team can confirm everyone is running the same commit. hermes plugins list prints the pin in its Source column (git pinned@<sha8>). Pins work for private repositories too, through the same stored credentials described below.

Installing from a private repository

hermes plugins install clones non-interactively (it never prompts for a username or password), so a private repo needs a credential Hermes can find on its own. For an ` source it tries, in order:

GITHUB_TOKEN or GH_TOKEN from your .env (GitHub hosts only).
The gh CLI's login (gh auth login), GitHub hosts only.
Your git credential helper (git credential fill) for that host — works for GitLab, Bitbucket and self-hosted servers if a credential is already stored.

The credential is sent as a one-shot HTTP header for that install or update; it is never written into the plugin's .git/config or the install metadata. SSH sources (git@host:owner/repo.git) authenticate through your ssh-agent as before. The same resolution applies to hermes plugins update, catalog MCP installs from git, and profile distributions fetched from a git URL.

What the allow-list does NOT gate

Several categories of plugin bypass plugins.enabled — they're part of Hermes' built-in surface and would break basic functionality if gated off by default:

Plugin kind	How it's activated instead
Bundled platform plugins (IRC, Teams, etc. under `plugins/platforms/`)	Auto-loaded so every shipped gateway channel is available. The actual channel turns on via `gateway.platforms.<name>.enabled` in `config.yaml`.
Bundled backends (image-gen providers under `plugins/image_gen/`, etc.)	Auto-loaded so the default backend "just works". Selection happens via `<category>.provider` in `config.yaml` (e.g. `image_gen.provider: openai`).
Memory providers (`plugins/memory/`)	All discovered; exactly one is active, chosen by `memory.provider` in `config.yaml`.
Context engines (`plugins/context_engine/`)	All discovered; one is active, chosen by `context.engine` in `config.yaml`.
Model providers (`plugins/model-providers/`)	All bundled providers under `plugins/model-providers/` discover and register at the first `get_provider_profile()` call. The user picks one at a time via `--provider` or `config.yaml`.
Pip-installed `backend` plugins	Opt-in via `plugins.enabled` (same as general plugins).
User-installed platforms (under `~/.hermes/plugins/platforms/`)	Opt-in via `plugins.enabled` — third-party gateway adapters need explicit consent.

In short: bundled "always-works" infrastructure loads automatically; third-party general plugins are opt-in. The plugins.enabled allow-list is the gate specifically for arbitrary code a user drops into ~/.hermes/plugins/.

Approval transports

An approval transport changes where a human sees and answers an existing Hermes tool-approval request. It does not decide whether a command needs approval and it is not an authorization-policy API.

python

def present(request):
    # Deliver request.command and request.description to your UI, wait for
    # its authenticated human response, then return a request-bound decision.
    choice = send_to_my_ui_and_wait(request)  # once/session/always/deny
    return request.respond(choice)


def register(ctx):
    ctx.register_approval_transport("my-ui", present)

present may be synchronous or async. Hermes runs it on a bounded worker and enforces the canonical approvals.timeout even if the plugin does not. The request is immutable and contains redacted display text, its host presentation class (cli or gateway), the host timeout, allowed choices, and an opaque request ID/digest. Return the result of request.respond(choice); unbound dictionaries and stale or changed request IDs/digests are rejected. A plugin cannot return a scope that the host did not offer (for example, always on a once-only request).

Registration alone does nothing. Enabling the plugin and explicitly selecting its transport are separate consent steps:

yaml

plugins:
  enabled: [my-approval-plugin]

security:
  approval:
    transport: my-ui
    transport_fallback: deny     # default

Transport exceptions, timeouts, unavailable registrations, invalid choices, and stale responses deny by default. To deliberately show the prompt on the ordinary CLI/TUI/gateway/ACP surface when the selected transport fails, set transport_fallback: builtin. Without that exact opt-in, Hermes never materializes the prompt on another surface.

Hermes still owns hardline blocks, sudo-stdin protection, user deny rules, request binding, allowed scopes, persistence, hooks, and final authorization. Hardline commands are blocked before any transport callback. There is intentionally no plugin approval policy, auto-allow callback, or required pre_tool_call policy in this interface. A future approval-policy capability may use the plugin capability-consent model, but transport selection does not grant it.

Migration for existing users

When you upgrade to a version of Hermes that has opt-in plugins (config schema v21+), any user plugins already installed under ~/.hermes/plugins/ that weren't already in plugins.disabled are automatically grandfathered into plugins.enabled. Your existing setup keeps working. Bundled standalone plugins are NOT grandfathered — even existing users have to opt in explicitly. (Bundled platform/backend plugins never needed grandfathering because they were never gated.)

Available hooks

Plugins can register the 27 lifecycle events currently accepted by hermes_cli.plugins.VALID_HOOKS. The Event Hooks catalog is canonical for exact timing, return handling, payload fields, and privacy notes.

Descriptive category	Shipped hooks
Directive/control	`pre_tool_call`, `pre_llm_call`, `pre_verify`, `pre_gateway_dispatch`
Transform	`transform_tool_result`, `transform_terminal_output`, `transform_llm_output`, `pre_transcription`
Observer	`post_tool_call`, `post_llm_call`, `pre_api_request`, `post_api_request`, `api_request_error`, `on_stream_start`, `on_stream_delta`, `on_stream_end`, `on_interim_message`, `on_session_start`, `on_session_end`, `on_session_finalize`, `on_session_reset`, `agent_loop_stopped`, `on_skill_lifecycle`, `subagent_start`, `subagent_stop`, `pre_approval_request`, `post_approval_response`, `pre_command`, `kanban_task_claimed`, `kanban_task_completed`, `kanban_task_blocked`

These categories describe current behavior rather than defining future naming rules. Plugin middleware remains a separate registry/surface.

Plugin types

Hermes has four kinds of plugins:

Type	What it does	Selection	Location
General plugins	Add tools, hooks, slash commands, CLI commands	Multi-select (enable/disable)	`~/.hermes/plugins/`
Memory providers	Replace or augment built-in memory	Single-select (one active)	`plugins/memory/`
Context engines	Replace the built-in context compressor	Single-select (one active)	`plugins/context_engine/`
Model providers	Declare an inference backend (OpenRouter, Anthropic, …)	Multi-register, picked by `--provider` / `config.yaml`	`plugins/model-providers/`

Memory providers and context engines are provider plugins — only one of each type can be active at a time. Model providers are also plugins, but many load simultaneously; the user picks one at a time via --provider or config.yaml. General plugins can be enabled in any combination.

Pluggable interfaces — where to go for each

The table above shows the four plugin categories, but within "General plugins" the PluginContext exposes several distinct extension points — and Hermes also accepts extensions outside the Python plugin system (config-driven backends, shell-hooked commands, external servers, etc.). Use this table to find the right doc for what you want to build:

Want to add…	How	Authoring guide
A tool the LLM can call	Python plugin — `ctx.register_tool()`	Build a Hermes Plugin · Adding Tools
A lifecycle hook (pre/post LLM, session start/end, tool filter)	Python plugin — `ctx.register_hook()`	Hooks reference · Build a Hermes Plugin
A slash command for the CLI / gateway	Python plugin — `ctx.register_command()`	Build a Hermes Plugin · Extending the CLI
A subcommand for `hermes <thing>`	Python plugin — `ctx.register_cli_command()`	Extending the CLI
A bundled skill that your plugin ships	Python plugin — `ctx.register_skill()`	Creating Skills
An inference backend (LLM provider: OpenAI-compat, Codex, Anthropic-Messages, Bedrock)	Provider plugin — `register_provider(ProviderProfile(...))` in `plugins/model-providers/<name>/`	Model Provider Plugins · Adding Providers
A gateway channel (Discord / Telegram / IRC / Teams / etc.)	Platform plugin — `ctx.register_platform()` in `plugins/platforms/<name>/`	Adding Platform Adapters
A memory backend (Honcho, Mem0, Supermemory, …)	Memory plugin — subclass `MemoryProvider` in `plugins/memory/<name>/`	Memory Provider Plugins
A context-compression strategy	Context-engine plugin — `ctx.register_context_engine()`	Context Engine Plugins
An image-generation backend (DALL·E, SDXL, …)	Backend plugin — `ctx.register_image_gen_provider()`	Image Generation Provider Plugins
A video-generation backend (Veo, Kling, Pixverse, Grok-Imagine, Runway, …)	Backend plugin — `ctx.register_video_gen_provider()`	Video Generation Provider Plugins
A TTS backend (any CLI — Piper, VoxCPM, Kokoro, xtts, voice-cloning scripts, …)	Config-driven (recommended) — declare under `tts.providers.<name>` with `type: command` in `config.yaml`. OR Python backend plugin — `ctx.register_tts_provider()` for Python-SDK / streaming engines that need more than a shell template.	TTS Setup · Python plugin guide
An STT backend (any CLI — whisper.cpp, custom whisper binary, local ASR CLI)	Config-driven (recommended) — declare under `stt.providers.<name>` with `type: command` in `config.yaml`, or set `HERMES_LOCAL_STT_COMMAND` for the legacy single-command escape hatch. OR Python backend plugin — `ctx.register_transcription_provider()` for Python-SDK engines (OpenRouter, SenseAudio, Gemini-STT, etc.).	STT Setup · Python plugin guide
External tools via MCP (filesystem, GitHub, Linear, Notion, any MCP server)	Config-driven — declare `mcp_servers.<name>` with `command:` / `url:` in `config.yaml`. Hermes auto-discovers the server's tools and registers them alongside built-ins.	MCP
Additional skill sources (custom GitHub repos, private skill indexes)	CLI — `hermes skills tap add <repo>`	Skills Hub · Publishing a custom tap
Gateway event hooks (fire on `gateway:startup`, `session:start`, `agent:end`, `command:*`)	Drop `HOOK.yaml` + `handler.py` into `~/.hermes/hooks/<name>/`	Event Hooks
Shell hooks (run a shell command on events — notifications, audit logs, desktop alerts)	Config-driven — declare under `hooks:` in `config.yaml`	Shell Hooks

:::note Not everything is a Python plugin. Some extension surfaces intentionally use config-driven shell commands (TTS, STT, shell hooks) so any CLI you already have becomes a plugin without writing Python. Others are external servers (MCP) the agent connects to and auto-registers tools from. And some are drop-in directories (gateway hooks) with their own manifest format. Pick the right surface for the integration style that fits your use case; the authoring guides in the table above each cover placeholders, discovery, and examples. :::

NixOS declarative plugins

On NixOS, plugins can be installed declaratively via the module options — no hermes plugins install needed. See the Nix Setup guide for full details.

nix

services.hermes-agent = {
  # Directory plugin (source tree with plugin.yaml)
  extraPlugins = [ (pkgs.fetchFromGitHub { ... }) ];
  # Entry-point plugin (pip package)
  extraPythonPackages = [ (pkgs.python312Packages.buildPythonPackage { ... }) ];
  # Enable in config
  settings.plugins.enabled = [ "my-plugin" ];
};

Declarative plugins are symlinked with a nix-managed- prefix — they coexist with manually installed plugins and are cleaned up automatically when removed from the Nix config.

Managing plugins

bash

hermes plugins                               # unified interactive UI
hermes plugins list                          # table: enabled / disabled / not enabled
hermes plugins search &lt;term>                 # search the Hermes plugin catalog
hermes plugins install &lt;name>                # install a catalog entry (repo @ reviewed pinned SHA)
hermes plugins install user/repo             # install from Git, then prompt Enable? [y/N]
hermes plugins install user/repo --enable    # install AND enable (no prompt)
hermes plugins install user/repo --no-enable # install but leave disabled (no prompt)
hermes plugins update my-plugin              # pull latest (local edits are autostashed and re-applied)
hermes plugins remove my-plugin              # uninstall
hermes plugins enable my-plugin              # add to allow-list
hermes plugins disable my-plugin             # remove from allow-list + add to disabled
hermes plugins capabilities [my-plugin]      # declared vs granted capabilities

One-click install links (Desktop)

Hermes Desktop registers the hermes:// URL scheme, so a website, README, or chat message can link straight to a plugin install:

hermes://plugin/install?repo=owner/repo            # main install link
hermes://plugin/install?repo=owner/repo&enable=1   # enable the agent plugin after install
hermes://plugin/install?repo=owner/repo&force=1    # replace an existing install

Clicking one opens Hermes and shows a confirmation dialog — the repo id, a "Before you install" note, and GitHub browse + clone links — then shallow-clones the repo to detect what it ships (an agent plugin — backend Python, a desktop plugin — app UI, or both). You pick the components with checkboxes and confirm. Nothing is installed until you do; deep links never auto-install, and agent-plugin installs go through the same install-time security scanning as hermes plugins install.

Hybrid repos (agent + desktop halves in one repo) use one link and one dialog. The same modal is reachable without a link via Capabilities → Plugins → Install from Git. Legacy hermes://plugin-agent/… and hermes://plugin-desktop/… URLs route into the same dialog. In dev builds (npm run dev) the scheme is hermes-dev://.

Websites need no SDK — a normal anchor works:

html

&lt;a href="hermes://plugin/install?repo=owner/repo&enable=1">Install in Hermes&lt;/a>

MCP servers have the equivalent link form — see Add to Hermes link.

Plugins can declare the privileged host surfaces they want in their plugin.yaml:

yaml

name: my-plugin
capabilities:
  - tools.override        # replace built-in tools
  - llm.model_override    # pick the model for host-owned LLM calls

When a plugin declares capabilities, hermes plugins install (and hermes plugins enable) shows the list with one-line risk descriptions and asks once. Consenting records the grant under plugins.entries.<id>.granted_capabilities together with a consent hash and timestamp. Declining leaves the plugin enabled with those capabilities off — a well-behaved plugin probes with ctx.has_capability() and degrades gracefully.

Update re-consent: if a plugin update declares capabilities you haven't granted, hermes plugins update surfaces the additions and asks again. New capabilities stay off until you consent — a plugin update can never silently widen its access.

Non-interactive sessions fail closed: installing or updating without a TTY completes the install, but declared capabilities are not granted. Run hermes plugins enable <id> interactively to grant them later.

Inspect the state at any time:

bash

hermes plugins capabilities             # all plugins with declared/granted capabilities
hermes plugins capabilities my-plugin   # one plugin, declared vs granted

Capability ids map 1:1 to the older per-feature config gates, which keep working but are deprecated in favor of the consent flow:

Capability	Legacy key (`plugins.entries.<id>.…`)
`tools.override`	`allow_tool_override`
`llm.provider_override`	`llm.allow_provider_override`
`llm.model_override`	`llm.allow_model_override`
`llm.agent_id_override`	`llm.allow_agent_id_override`
`llm.profile_override`	`llm.allow_profile_override`
`llm.task_override`	`llm.allow_task_override`
`gateway.platform_actions`	`allow_platform_actions`

A gate is open when either the capability is granted or the legacy key is set — existing configs keep working unchanged.

Not a sandbox

Capabilities are a consent and audit layer, not isolation. Plugins run as regular in-process Python: a malicious plugin can ignore every gate here. Granting a capability is a statement of trust in the plugin author — it is not a code audit, and Hermes has not reviewed the plugin's code. Only install plugins from sources you trust.

Platform actions

ctx.platform_actions gives a plugin a minimal, capability-gated verb set for acting on connected chat platforms through the live gateway adapter registry — the sanctioned alternative to monkeypatching an adapter. It is off by default: every call re-checks the gateway.platform_actions capability (legacy key plugins.entries.<id>.allow_platform_actions), and an ungranted call returns a structured error instead of acting.

v1 verbs (both async, both return a plain dict, and neither ever raises into hook dispatch):

python

result = await ctx.platform_actions.add_reaction(
    platform="telegram", chat_id="-100123", message_id="456", emoji="👍",
)
result = await ctx.platform_actions.set_thread_title(
    platform="discord", chat_id="123", thread_id="456", title="New title",
)
if not result["ok"]:
    print(result["error"], result.get("detail"))

Success is {"ok": True, "action": <verb>}. Failures are {"ok": False, "error": <code>, "detail": <str>} with stable error codes: capability_not_granted, invalid_argument, gateway_unavailable, unknown_platform, adapter_not_registered, adapter_disconnected, unsupported_platform_action, action_failed. Actions validate that the target adapter exists and is connected before acting; a disconnected or missing adapter degrades to a structured error, never an exception.

Platforms supported in v1: Telegram and Discord. Telegram's add_reactionsets the bot's reaction (the Bot API replaces a previous bot reaction rather than stacking). Every action — allowed or denied — is written to the log with the plugin id, verb, platform, and outcome.

Security note

Platform actions are a messaging-as-the-bot power: a granted plugin can react and rename threads in any chat the gateway bot can reach, not just the chat that triggered the hook. Grant gateway.platform_actions only to plugins you trust, and prefer plugins that document exactly which actions they take. Raw platform SDK payload/handle access is deliberately not part of this surface — per the #64176 round-2 design correction it requires its own capability (gateway.raw_events) with a "no stability guarantee" label and a separate design, and has not shipped.

Discovering plugins — the Hermes plugin catalog

hermes plugins search <term> searches the Hermes plugin catalog — the curated, SHA-pinned catalog maintained in the hermes-agent repository (plugin-catalog/). Matching covers entry names, descriptions, and declared tools:

bash

hermes plugins search telegram    # search the catalog
hermes plugins browse             # browse every entry
hermes plugins info &lt;name>        # full details for one entry

Once you've found a plugin, install it by bare name — the name resolves to the entry's repository at its pinned commit SHA, and catalog provenance is recorded so hermes plugins update can re-pin when the catalog moves:

bash

hermes plugins install &lt;catalog-name>

Explicit owner/repo or Git-URL identifiers never touch the catalog and are flagged as custom (unreviewed) sources. An explicit --ref <40-char commit SHA> pins a custom install.

See Plugin Catalog for the full trust model, admission CI, and submission workflow.

Cataloged ≠ audited

A catalog entry means the entry's metadata and declared capabilities were reviewed at admission — it is not a code audit. Installing still goes through the normal consent flow (plugins install disabled by default, enabling is an explicit step, and tool-override rights require a separate grant). Review a plugin's source before enabling it.

Plugin packs

A plugin pack is a declarative, shareable YAML file (hermes-pack.yaml) that pins a set of plugins — like sharing a modpack. Installing a pack fans out to ordinary pinned installs; nothing new exists at runtime.

yaml

name: voice-assistant-pack
description: STT + streaming TTS + approval relay
author: hyper
version: 1.0.0
plugins:
  - name: hermes-telegram-business       # bare plugin-catalog name…
    ref: e905f3bc5eeaa5a9dab9bc5155601b3ebec75757
  - repo: owner/approval-relay           # …or explicit owner/repo (or git URL)
    ref: 8f3c2d1a9b4e5f6071829304a5b6c7d8e9f00112
    subdir: plugins/relay                # optional monorepo path
config:                                  # optional, non-secret seeds only
  hermes-media-studio:
    default_model: flux-3
skills: []                               # declared list only (not auto-installed yet)

bash

hermes plugins pack show ./hermes-pack.yaml     # dry-run review
hermes plugins pack install ./hermes-pack.yaml  # review → confirm → install
hermes plugins pack export > hermes-pack.yaml   # snapshot the current install
hermes plugins pack export --enabled-only       # only plugins.enabled

Supply-chain posture. Every entry's ref must be an exact 40-character commit SHA — tags and branch names are rejected with an error naming the entry, the same rule as the plugin catalog. Pack installs ride the exact same pinned install path as hermes plugins install --ref <sha> and record the same provenance in plugins/.install-metadata.json, so two installs of the same pack resolve identically. Packs build on the manifest v2 fields (manifest_version, api_version, requires_plugins) — each plugin's own manifest still validates through the normal install path.

Consent is never bulk-granted. pack install shows a mandatory review screen (every plugin, source, pinned ref, and the capabilities it declares), then asks one confirmation for the pack contents. After that, each plugin's declared capabilities go through the standard per-plugin capability-consent prompt — identical to a single hermes plugins install. There is no --yes, and non-interactive sessions cannot install packs.

Secrets never travel in packs. config: seeds are limited to non-secret plugins.entries.<id> keys — secret-shaped key names (*token*, *key*, *password*, …), capability grants, and the deprecated allow_* trust gates are rejected on install and stripped on export. Plugins that need secrets declare them in their own requires_env, which prompts during install as usual. Existing user values in plugins.entries.<id> always win over pack seeds.

Partial failure. Each plugin installs independently; failures are reported per plugin, the rest continue, and the command exits non-zero if any plugin failed.

Export caveats. pack export only includes plugins with known Git provenance (installed via hermes plugins install). Local-only plugins are listed as warning comments in the emitted YAML, not as installable entries.

The skills: list is parsed and displayed at install time but not yet auto-installed — install those manually for now (hermes skills). Wiring skill-hub ids into pack install is a documented follow-up seam.

Install-time security scanning

Every hermes plugins install and hermes plugins update runs a static security scan over the plugin tree before it is activated (inspired by Claude Cowork's skill & plugin security scanning). The scanner reuses the same threat-pattern engine as the Skills Hub guard — exfiltration of credential stores, reverse shells, destructive commands, persistence mechanisms, obfuscated execution, and prompt injection in documentation files — with plugin-aware exemptions: a provider plugin reading its own API key from the environment (the documented requires_env pattern) is not flagged.

Three verdicts, matching Cowork's pass/warn/fail:

Verdict	Behavior
safe	Installs normally, no extra output
caution	Findings are shown; you confirm `Install anyway? [y/N]` (or pass `--force`)
dangerous	Blocked. `--force` does not override

On hermes plugins update, a dangerous verdict on the updated tree disables the plugin until you review the findings and re-enable it.

Scanning is on by default; disable it in config.yaml:

yaml

plugins:
  scan_on_install: false

Interactive UI

Running hermes plugins with no arguments opens a composite interactive screen:

Plugins
  ↑↓ navigate  SPACE toggle  ENTER configure/confirm  ESC done

  General Plugins
 → [✓] my-tool-plugin — Custom search tool
   [ ] webhook-notifier — Event hooks
   [ ] disk-cleanup — Auto-cleanup of ephemeral files [bundled]

  Provider Plugins
     Memory Provider          ▸ honcho
     Context Engine           ▸ compressor

General Plugins section — checkboxes, toggle with SPACE. Checked = in plugins.enabled, unchecked = in plugins.disabled (explicit off).
Provider Plugins section — shows current selection. Press ENTER to drill into a radio picker where you choose one active provider.
Bundled plugins appear in the same list with a [bundled] tag.

Provider plugin selections are saved to config.yaml:

yaml

memory:
  provider: "honcho"      # empty string = built-in only

context:
  engine: "compressor"    # default built-in compressor

Enabled vs. disabled vs. neither

Plugins occupy one of three states:

State	Meaning	In `plugins.enabled`?	In `plugins.disabled`?
`enabled`	Loaded on next session	Yes	No
`disabled`	Explicitly off — won't load even if also in `enabled`	(irrelevant)	Yes
`not enabled`	Discovered but never opted in	No	No

The default for a newly-installed or bundled plugin is not enabled. hermes plugins list shows all three distinct states so you can tell what's been explicitly turned off vs. what's just waiting to be enabled.

In a running session, /plugins shows which plugins are currently loaded.

Injecting Messages

Plugins can inject messages into a CLI conversation or a known gateway session using ctx.inject_message():

python

# Active CLI conversation
ctx.inject_message("New data arrived from the webhook", role="user")

# Existing gateway conversation
ctx.inject_message(
    "New data arrived from the webhook",
    role="user",
    session_key="agent:main:telegram:dm:123456789",
)

Signature: ctx.inject_message(content: str, role: str = "user", *, session_key: str | None = None) -> bool

In CLI mode:

If the agent is idle (waiting for user input), the message is queued as the next input and starts a new turn.
If the agent is mid-turn (actively running), the message interrupts the current operation — the same as a user typing a new message and pressing Enter.
For non-"user" roles, the content is prefixed with [role] (e.g. [system] ...).
Returns True if the message was queued successfully.

In gateway mode:

session_key is required and must identify an existing gateway session. It is the stable routing key, not the CLI session ID.
Hermes reuses that session's stored platform, chat, thread, profile, and conversation history. Plugins cannot supply a new chat route through this API.
Hermes rechecks the stored route against the gateway's current authorisation rules before dispatch.
Routes that relied only on an adapter-time or upstream authorisation decision are rejected unless Hermes can revalidate them from current core allowlists, pairing, or explicit allow-all configuration.
Injected text is always conversational input. It cannot invoke slash commands, approve tools, or resolve pending confirmation and clarification prompts.
The route and conversation are pinned while dispatch is pending. Hermes drops the request if topic recovery changes the route or the session rotates before handling starts.
The request enters the platform adapter's normal message path. Active sessions use the existing busy-session queue rather than starting a competing turn.
Returns True when the live gateway accepts the request for asynchronous dispatch. This does not confirm that the agent turn or platform delivery has completed.
Returns False when session_key is omitted, the permission is not granted, or no live gateway can accept the request. Unknown or unroutable session keys discovered after asynchronous acceptance are written to the gateway log.

This enables plugins like remote control viewers, messaging bridges, or webhook receivers to feed messages into the conversation from external sources.

Gateway injection can send an agent response to an external messaging platform. It is disabled by default for every plugin. Grant it per plugin in config.yaml:

yaml

plugins:
  entries:
    my-plugin:
      allow_gateway_injection: true

WARNING

Only grant gateway injection to plugins you trust. Hermes checks this host API permission and restricts it to existing session routes, but Python plugins run in-process and this setting is not a sandbox.

:::note This plugin API does not expose a public HTTP endpoint or CLI command for external processes. The plugin must already know the target gateway session_key, for example from its own trusted configuration or previously retained session state. :::

Calling MCP servers from plugins

ctx.call_mcp() lets a plugin call a tool on one of the user's configured MCP servers — synchronously, from any hook or tool handler — routing through Hermes' existing native MCP client (same connections, trust-tier gates, circuit breaker, and reconnect logic as model-invoked MCP tools; never a parallel client).

python

result = ctx.call_mcp(
    "knowledge_rag",            # server name from mcp.servers
    "query_knowledge",          # tool on that server
    {"query": "deploy runbook"},
    timeout=30,                 # seconds; clamped to 1–600
)
if result["ok"]:
    print(result["result"])
else:
    print("MCP error:", result["error"])

Signature: ctx.call_mcp(server: str, tool: str, arguments: dict | None = None, timeout: float = 30) -> dict

Returns a stable envelope: {"ok": True, "result": ...} (plus structuredContent when the server provides it) or {"ok": False, "error": "..."}. Results over ~64 KB are truncated and flagged with "truncated": True.

Security: default-off, per-server allowlist

A plugin has no MCP access by default. The operator must grant each server explicitly in config.yaml:

yaml

plugins:
  entries:
    my-plugin:
      mcp_allowlist: ["knowledge_rag", "github"]

Calling a server not in the list raises PermissionError naming the exact config key to set.
The grant is per-server and per-plugin — never ambient authority over every configured server, and "*" wildcards are not honored.
Every call has an enforced timeout (default 30 s) so a hung MCP server cannot stall the hook or tool pipeline that invoked it.
MCP servers return untrusted content. Treat result as data, not instructions — don't feed it into privileged decisions (approvals, command execution) without validation.

WARNING

Granting mcp_allowlist gives the plugin the same access to that MCP server as the model has — including any write-capable tools the server exposes (subject to the server's trust tier gates). Grant only servers the plugin genuinely needs.

See the full guide for handler contracts, schema format, hook behavior, error handling, and common mistakes.

Open Webui

Bundled

Apple

Autonomous Ai Agents

Creative

Devops

Email

Github

Media

Mlops

Note Taking

Productivity

Research

Smart Home

Social Media

Software Development

Web

Optional

Autonomous Ai Agents

Blockchain

Communication

Creative

Data Science

Devops

Dogfood

Email

Finance

Gaming

Health

Mcp

Migration

Mlops

Payments

Productivity

Research

Security

Smart Home

Social Media

Software Development

Web Development

Yuanbao

Files

Features

Messaging

Skills

Bundled

Optional

Plugins ​

Quick overview ​

Minimal working example ​

What plugins can do ​

Plugin discovery ​

Plugin sub-categories ​

Plugins are opt-in (with a few exceptions) ​

Installing from a private repository ​

What the allow-list does NOT gate ​

Approval transports ​

Migration for existing users ​

Available hooks ​

Plugin types ​

Pluggable interfaces — where to go for each ​

NixOS declarative plugins ​

Managing plugins ​

One-click install links (Desktop) ​

Plugin capabilities and consent ​

Platform actions ​

Discovering plugins — the Hermes plugin catalog ​

Plugin packs ​

Install-time security scanning ​

Interactive UI ​

Enabled vs. disabled vs. neither ​

Injecting Messages ​

Calling MCP servers from plugins ​

Security: default-off, per-server allowlist ​

Plugins

Quick overview

Minimal working example

What plugins can do

Plugin discovery

Plugin sub-categories

Plugins are opt-in (with a few exceptions)

Installing from a private repository

What the allow-list does NOT gate

Approval transports

Migration for existing users

Available hooks

Plugin types

Pluggable interfaces — where to go for each

NixOS declarative plugins

Managing plugins

One-click install links (Desktop)

Plugin capabilities and consent

Platform actions

Discovering plugins — the Hermes plugin catalog

Plugin packs

Install-time security scanning

Interactive UI

Enabled vs. disabled vs. neither

Injecting Messages

Calling MCP servers from plugins

Security: default-off, per-server allowlist