The Banking MCP Server defines 4 tools with explicit schemas and descriptions in src/mcp/server.py. All tools follow verb_noun naming (get_*, search_*) which is correct. However, significant issues reduce quality: (1) API key is exposed as a tool parameter across all 4 tools, violating the secret-injection pattern, credentials must never be parameters; (2) Descriptions are minimal (10-27 chars) and lack context for LLM selection, they state WHAT but not WHEN or WHY to call; (3) No documented output schemas, LLMs cannot infer return structure or plan downstream calls; (4) Error handling is basic (status/error fields) with no recovery guidance; (5) No tool annotations (readOnlyHint, etc.) despite all being read-only operations. Positives: schemas are present and properly typed, all parameters have descriptions, naming is clear and unambiguous.

• Remove api_key from all tool parameters. Move to server-side secret injection: load MCP_API_KEY from environment (already done in code, src/mcp/server.py line 'MCP_API_KEY = os.getenv("MCP_API_KEY", ...)', but now validate inside _require_auth without exposing it to LLMs). Clients should authenticate via MCP protocol, not pass keys in every call.
• Expand tool descriptions to 50-150 characters, adding WHEN and WHY context. E.g. 'get_customer_info': 'Retrieve customer profile including name, age, email, and account type. Use this when you need demographic or account setup info. Returns a single customer record.'
• Document output schemas for each tool. Add an 'outputSchema' field to each types.Tool() or document in description. E.g. 'Returns {status: string, customer: {id: int, name: string, age: int, email: string, account_type: string, balance: float}}'.
• Add readOnlyHint: true to all 4 tool definitions. Update types.Tool() calls to include this hint so agents know these are safe for speculation.
• Improve error messages with recovery guidance. E.g. 'Customer {customer_id} not found. Tip: search_bank_products with a customer name fragment first if you don't have their ID.'
• For get_last_transactions, document pagination in description: 'Returns up to N (default 5) most recent transactions, ordered by date DESC. Pass limit=50 to retrieve more; to fetch older transactions, add an offset parameter or fetch by date range.'
• Standardize response field names. Currently get_customer_info returns 'customer' object, but get_account_balance returns 'account_balance' float directly. Consider returning {status, data: {balance}} for consistency and easier chaining.