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Hermes Plugins: Extending Your Agent

By Hermes Agent· · 4 min read

A complete guide to Hermes Agent's plugin system — listing, installing, removing plugins, and understanding what plugins can add to your agent.

TLDR: Hermes supports plugins (hermes extensibility) for adding new commands, tools, memory backends, and integrations. Manage them with hermes plugins list, hermes plugins install NAME, and hermes plugins remove NAME. Plugins are community-contributed packages that extend what your agent can do without modifying core code.

Key Takeaways

  • Plugins add new functionality without touching core code
  • Manage with hermes plugins list/install/remove
  • Use /plugins in-session to see what’s loaded
  • Plugins can add: tools, slash commands, platform adapters, memory backends
  • Community plugins are installable by name
  • Custom plugins can be developed locally

What Are Plugins?

Plugins are self-contained packages that extend Hermes Agent. Unlike skills (which are procedural knowledge documents), plugins are actual code that add new capabilities — new tools, new slash commands, new platform integrations, even new memory backends.

The plugin system is how Hermes stays extensible without bloating the core. If there’s something Hermes can’t do out of the box, there’s probably a plugin for it — or you can write one.

Managing Plugins

Listing Plugins

hermes plugins list

Shows all installed plugins and their status (enabled/disabled).

In-session:

/plugins

Installing Plugins

hermes plugins install NAME

Replace NAME with the plugin’s identifier. Plugins are fetched from the official registry.

Removing Plugins

hermes plugins remove NAME

This uninstalls the plugin cleanly — no leftover config or dependencies.

What Plugins Can Do

Plugins extend Hermes in four main categories:

1. New Tools

Plugins can register new tool calls that the agent can use. Examples:

  • A weather tool that checks weather forecasts
  • A jira tool that queries Jira tickets
  • A docker tool that manages containers

Tools added by plugins appear alongside built-in tools in the agent’s toolset.

2. New Slash Commands

Plugins can add custom /commands. Examples:

  • /deploy — trigger a deployment
  • /jira-search — search Jira from within a session

3. Platform Adapters

Plugins can add new messaging platforms to the gateway. While Hermes supports 15+ platforms natively, plugins can add niche ones.

4. Memory Backends

Plugins can add custom memory storage backends, like the Honcho plugin for external memory.

Built-in / Official Plugins

Some notable plugins shipped with Hermes:

PluginWhat it adds
HonchoExternal memory backend with dialectic user modeling
KanbanMulti-agent work queue and orchestration board

Creating Custom Plugins

For developers who want to build their own plugins:

  1. Create a Python package following the Hermes plugin API
  2. Register new tools, commands, or adapters using the plugin decorators
  3. Place it in ~/.hermes/plugins/ or publish to the registry

The plugin API is documented in the developer guide.

Plugins vs Skills vs MCP

These three extension mechanisms serve different purposes:

MechanismWhat it isWhen to use
SkillsMarkdown procedure documentsTeaching the agent how to do something
PluginsPython code packagesAdding new capabilities (tools, commands)
MCP ServersExternal services via protocolConnecting to external APIs and databases

Skills change what the agent knows. Plugins change what the agent can do. MCP servers change what the agent can reach.

Example: Installing the Honcho Plugin

# Install
hermes plugins install honcho

# Configure
hermes config set memory.provider "honcho"

# Verify
hermes plugins list
# → honcho (enabled)

This replaces the built-in SQLite memory with Honcho’s cloud-based memory, giving you cross-device memory sync and advanced user modeling.

FAQ

Q: Are plugins safe to install? Plugins from the official registry are vetted. Custom plugins run with the same permissions as the agent — review any plugin code before installing from untrusted sources.

Q: Do plugins persist across Hermes updates? Yes — plugins are stored separately from the core code and survive updates.

Q: Can I disable a plugin without removing it? Plugin management is all-or-nothing per plugin. To temporarily disable, remove and reinstall later.

Q: What’s the difference between a plugin and a skill? Skills are markdown files the agent reads as instructions. Plugins are code that add new tools and commands. Skills change what the agent knows; plugins change what it can do.

Q: How do I find available plugins? Run hermes plugins list to see installed ones. For discoverable plugins, check the Hermes documentation and community channels.

Next Steps