Calendar Events MCP has well-structured tool definitions with complete input schemas and descriptions for all 5 tools. All tools follow verb_noun naming (get_*, list_, search_). Descriptions are present and adequate (100-150 chars typical). However, output schemas are not documented, LLMs cannot infer what fields to expect in responses. Parameter descriptions lack format constraints (e.g., date format is stated but not validated). No error handling guidance. No tool annotations (readOnlyHint, etc.). All tools are read-only, which is appropriate, but this is not declared in the schema.

• Document output schemas for all tools. Example for get_events: 'Returns {"events": [{"id": string, "title": string, "start": ISO8601, "end": ISO8601, "calendar": string, "all_day": boolean}], "events_error": string|null}'.
• Add readOnlyHint: true to all tool schemas to signal to agents that these tools are safe to retry and do not modify state.
• Add regex pattern to date parameters: 'from_date' should have pattern '^\d{4}-\d{2}-\d{2}$' in the JSON Schema, and description should state 'Must be YYYY-MM-DD format (e.g., 2024-01-15)'.
• Add error recovery guidance: 'If no events found, try expanding the date range or calling list_calendars() to verify calendar names.'
• Document result limits: 'Returns up to 100 events. Use from_date and to_date to narrow results. If more than 100 events exist, results are truncated.'

Inferred effective spec: <=2025-11-25.

• Relies on Logging (deprecated) - log to stderr or use OpenTelemetry