Firestore MCP has complete input schemas with types and descriptions for all 7 tools, which is a strong foundation. Tool names follow verb_noun convention (getDocument, createDocument, etc.). However, descriptions are generic and lack LLM-optimized guidance on WHEN to use each tool vs alternatives. Parameter descriptions are present but minimal (avg ~40 chars vs baseline 72). Output schemas are not documented, LLMs cannot predict response structure. Error handling is absent; no recovery guidance or actionable error messages. Security concerns: project parameter is exposed as optional input rather than server-side injection. No idempotency hints despite write operations. Composition is sound (single responsibility per tool), but missing pagination guidance for queryDocuments and listPrompts despite returning arrays.

• Add output schema documentation for each tool. Example: 'Returns: {success: boolean, data: {id: string, collection: string, fields: object}, timestamp: ISO8601}'. This enables LLMs to chain tools and extract required fields.
• Expand tool descriptions to 100-200 chars with WHEN/WHY guidance. Example for updateDocument: 'Update fields in an existing Firestore document. Use this to modify specific fields without replacing the entire document. Set merge=true (default) to preserve unspecified fields, or merge=false to replace all fields.'
• Add error handling with recovery hints. Wrap tool implementations to catch Firestore errors and return: {error: 'Collection not found', suggestion: 'Available collections: users, posts, comments', retryable: false}.
• Move project parameter to server-side configuration via GOOGLE_CLOUD_PROJECTS env var only. Remove it from tool inputs. If multi-project support is needed, use a separate admin tool or configuration endpoint, not per-call parameters.
• Add pagination to queryDocuments and listPrompts: accept limit (default 20, max 100) and offset/cursor parameters. Return {results: [...], total: number, hasMore: boolean, nextCursor: string}. Document in descriptions: 'Results are limited to 20 per call. Use offset/cursor for pagination.'