# event The Event to which a Hook subscribes. Required on every Hook. Chooses the Event the Hook listens to before its `filter`, `when`, `shell`, and owned `action` run: ```json { "local": { "no-env-access": { "description": "Blocks reads and writes to .env files.", "event": "tool_call", "shell": "false" } } } ``` - **Type** string enum · required · every Hook - One of the 8 supported Events: `tool_call`, `tool_result`, `turn_end`, `agent_end`, `agent_settled`, `session_before_switch`, `session_before_fork`, and the reactive `hook_result`. - [Events](../events.md) documents what each Event carries and when it fires. `hook_result` observes other Hooks' results; the [filter](filter.md) page lists its candidate fields.