# Skills, commands, and MCP servers

> Discover provider-native skills and control the external tools available to sessions.

Canonical URL: https://docs.zuse.sh/composer/skills-mcp



Zuse keeps provider-native extensions visible without inventing a second configuration format.

## Skills [#skills]

For Claude Code and Codex, the composer discovers global and project skills from the provider's native skill directories. Type `/` to search built-in commands and discovered skills. The list refreshes when relevant skill files change.

A selected skill is passed to the active provider with its name and arguments. Read a third-party skill before running it: skill instructions can ask the agent to use tools, access services, or modify files, and the session's permission posture still governs those actions.

Zuse also installs its own [bundled skill](/reference/bundled-skill.md) for configuration and troubleshooting help.

## Built-in commands [#built-in-commands]

Commands such as `/new`, `/model`, `/mode`, `/plan`, `/run`, and `/help` are handled by Zuse. The same picker can surface provider commands. Those commands are sent to the provider as written, so their exact behavior follows the installed provider version.

Only commands applicable to the active provider appear. Goal mode is exposed for supported Codex and Grok versions.

## MCP servers and connected apps [#mcp-servers-and-connected-apps]

Open **Settings → MCP Servers** to see a reconciled inventory of:

* Zuse's built-in tool server;
* Claude user, project, local, plugin, and connected-app servers;
* Codex-configured servers and provider-reported apps.

Zuse reads the providers' native configuration as the source of truth. It does not keep a duplicate MCP registry. Add definitions with the provider's own tooling or configuration files, then refresh the inventory in Zuse.

The settings pane shows connection state, tool count, missing requirements, and authentication needs. Supported entries can be connected, enabled, or disabled from Zuse. Global disabled-server overrides live in user settings; repository overrides live in `.zuse/settings.toml` as `mcp_disabled_servers`.

Disabling a server changes new session availability. Restart or recreate an existing provider session when its process has already loaded an older tool configuration.