Mods vs hooks vs skills vs MCP
Match the mechanism to the job
Several mechanisms can coexist in one workflow. Choose based on the behavior you need, then keep each component small enough to inspect.
| Mechanism | Main purpose | Useful example | Review concern |
|---|---|---|---|
| Mod | Event handlers and session UI | Live counter or pane | Code, dependencies and permissions |
| Classic hook | Run configured actions on events | Validate a change | Shell commands and exit behavior |
| Skill | Give Claude a reusable procedure | Review a release | Instructions and tools it may invoke |
| MCP | Connect a tool or data service | Query a remote catalog | Server access and returned data |
Compose without confusing responsibilities
A skill can explain when to use a tool exposed by an MCP server. A classic hook can perform a fixed check. A mod can display progress. None of these choices removes the need to authorize sensitive operations. Remote service text and repository content remain untrusted input.
A practical decision sequence
If the task is mainly instructions, write a skill. If it is a fixed action at an event, try a classic hook. If it needs session interaction or a persistent interface, examine a mod. If the missing capability lives in a separate service, examine MCP. Before switching mechanisms, list what state, credentials and failure handling the workflow actually needs.