Capabilities
Capabilities
What you can give an agent beyond a voice — tools, hooks, skills, MCP servers, and durable state.
An agent starts as instructions and a voice. Each page in this section adds one capability to it, and every capability composes with the others — an agent can carry tools, hooks, skills, and MCP servers at once.
| Capability | What it adds |
|---|---|
| Tools | Let the model act — client, background client, and server tools, with schemas and the dispatch lifecycle |
| Hooks | Intercept the lifecycle — inject context, deny or rewrite tool calls, observe outcomes |
| Skills | Load SKILL.md playbooks just-in-time, keeping the prompt small and the expertise on demand |
| Plugins | Bundle instructions, skills, tools, and hooks for reuse |
| MCP servers | Attach tools from any Model Context Protocol server without writing handlers |
| Session state | A durable key-value store the agent writes with tools and your client observes as events |
Tools are the foundation — hooks guard them, skills and MCP servers supply them, and state is written through them. If you're new to the section, read Tools first.