Files
hermes-agent/website/docs/user-guide/features/plugins.md
Teknium 8da410ed95 feat(plugins): add slash command registration for plugins (#2359)
Plugins can now register slash commands via ctx.register_command()
in their register() function. Commands automatically appear in:
- /help and COMMANDS_BY_CATEGORY (under 'Plugins' category)
- Tab autocomplete in CLI
- Telegram bot menu
- Slack subcommand mapping
- Gateway dispatch

Handler signature: handler(args: str) -> str | None
Async handlers are supported in gateway context.

Changes:
- commands.py: add register_plugin_command() and rebuild_lookups()
- plugins.py: add register_command() to PluginContext, track in
  PluginManager._plugin_commands and LoadedPlugin.commands_registered
- cli.py: dispatch plugin commands in process_command()
- gateway/run.py: dispatch plugin commands before skill commands
- tests: 5 new tests for registration, help, tracking, handler, gateway
- docs: update plugins feature page and build guide
2026-03-21 16:00:30 -07:00

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3.3 KiB
Markdown

---
sidebar_position: 20
---
# Plugins
Hermes has a plugin system for adding custom tools, hooks, slash commands, and integrations without modifying core code.
**→ [Build a Hermes Plugin](/docs/guides/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.
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
| Capability | How |
|-----------|-----|
| Add tools | `ctx.register_tool(name, schema, handler)` |
| Add hooks | `ctx.register_hook("post_tool_call", callback)` |
| Add slash commands | `ctx.register_command("mycommand", handler)` |
| Ship data files | `Path(__file__).parent / "data" / "file.yaml"` |
| Bundle skills | Copy `skill.md` to `~/.hermes/skills/` at load time |
| Gate on env vars | `requires_env: [API_KEY]` in plugin.yaml |
| Distribute via pip | `[project.entry-points."hermes_agent.plugins"]` |
## Plugin discovery
| Source | Path | Use case |
|--------|------|----------|
| 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 |
## Available hooks
| Hook | Fires when |
|------|-----------|
| `pre_tool_call` | Before any tool executes |
| `post_tool_call` | After any tool returns |
| `pre_llm_call` | Before LLM API request |
| `post_llm_call` | After LLM API response |
| `on_session_start` | Session begins |
| `on_session_end` | Session ends |
## Slash commands
Plugins can register slash commands that work in both CLI and messaging platforms:
```python
def register(ctx):
ctx.register_command(
name="greet",
handler=lambda args: f"Hello, {args or 'world'}!",
description="Greet someone",
args_hint="[name]",
aliases=("hi",),
)
```
The handler receives the argument string (everything after `/greet`) and returns a string to display. Registered commands automatically appear in `/help`, tab autocomplete, Telegram bot menu, and Slack subcommand mapping.
| Parameter | Description |
|-----------|-------------|
| `name` | Command name without slash |
| `handler` | Callable that takes `args: str` and returns `str | None` |
| `description` | Shown in `/help` |
| `args_hint` | Usage hint, e.g. `"[name]"` |
| `aliases` | Tuple of alternative names |
| `cli_only` | Only available in CLI |
| `gateway_only` | Only available in messaging platforms |
## Managing plugins
```
/plugins # list loaded plugins in a session
hermes config set display.show_cost true # show cost in status bar
```
See the **[full guide](/docs/guides/build-a-hermes-plugin)** for handler contracts, schema format, hook behavior, error handling, and common mistakes.