docs: Promote safety to top-level page

why: Safety is a product differentiator and belongs in the main nav,
not buried under topics/.
what:
- Move docs/topics/safety.md to docs/safety.md
- Add tool annotations table (readOnly, destructive, idempotent per tool)
- Delete docs/topics/index.md (orphan toctree wrapper)

Author: tony

docs/topics/safety.md docs/safety.mddocs/topics/safety.md renamed to docs/safety.md

@@ -60,3 +60,37 @@ Destructive tools include safeguards against self-harm:
 - `kill_pane` refuses to kill the pane running the MCP server
 
 These protections use the `TMUX_PANE` environment variable to detect the caller's own pane.
+
+## Tool annotations
+
+Each tool carries MCP tool annotations that hint at its behavior:
+
+| Tool | Tier | readOnly | destructive | idempotent |
+|------|------|----------|-------------|------------|
+| `list_sessions` | readonly | true | false | true |
+| `get_server_info` | readonly | true | false | true |
+| `list_windows` | readonly | true | false | true |
+| `list_panes` | readonly | true | false | true |
+| `capture_pane` | readonly | true | false | true |
+| `get_pane_info` | readonly | true | false | true |
+| `search_panes` | readonly | true | false | true |
+| `wait_for_text` | readonly | true | false | true |
+| `show_option` | readonly | true | false | true |
+| `show_environment` | readonly | true | false | true |
+| `create_session` | mutating | false | false | false |
+| `create_window` | mutating | false | false | false |
+| `split_window` | mutating | false | false | false |
+| `send_keys` | mutating | false | false | false |
+| `rename_session` | mutating | false | false | true |
+| `rename_window` | mutating | false | false | true |
+| `resize_pane` | mutating | false | false | true |
+| `resize_window` | mutating | false | false | true |
+| `set_pane_title` | mutating | false | false | true |
+| `clear_pane` | mutating | false | false | true |
+| `select_layout` | mutating | false | false | true |
+| `set_option` | mutating | false | false | true |
+| `set_environment` | mutating | false | false | true |
+| `kill_server` | destructive | false | true | false |
+| `kill_session` | destructive | false | true | false |
+| `kill_window` | destructive | false | true | false |
+| `kill_pane` | destructive | false | true | false |