Single tool 'watch' has a clear, action-oriented name and a detailed description (180+ chars) explaining what it does, when to use it, and the backing implementation. Input schema is well-structured with typed parameters (string, boolean, array of enums) and descriptions for each. However, the tool lacks output schema documentation, the description mentions 'resource-change ticks' and references WatchEvent but does not formally document what fields the emitted event contains or what the agent should expect. Error handling is present (InvalidSpec, Subscribe errors) but lacks recovery guidance. The tool is read-only and non-destructive, reducing risk, but the output contract is incomplete.

• Document the output schema explicitly. Add to the tool description or a separate schema section: 'Emits a WatchEvent with fields: {"type": "resource_change", "resource_uri": "<watched-path>", "timestamp": "<ISO-8601>"}' or equivalent.
• Enhance error messages with actionable recovery steps. E.g., 'InvalidSpec: path must not be empty, provide a non-empty file or directory path' and 'Subscribe: failed to watch path, verify the path exists and the process has read permissions.'
• Add parameter constraints to the description. E.g., 'path: absolute or relative filesystem path (must exist and be readable); recursive: applies only to directories; event_kinds: filter which filesystem events trigger a tick (default: create, modify, remove).'
• Clarify the lifecycle and cancellation semantics. Document that dropping the watch handle stops the native watcher synchronously and no further ticks are emitted.
• Consider adding a 'debounce_ms' parameter to coalesce rapid filesystem events, reducing noise for high-frequency watchers.