Single tool with adequate naming (get_bin_data_tool) but significant gaps in schema documentation and parameter descriptions. Tool description is present (28 chars) but minimal. Input schema visible with 'bin' parameter typed as string with basic description. No output schema documented. No error handling guidance. No parameter constraints (e.g., BIN format, length). Formatting function suggests complex nested response structure, but this is not formally documented for the LLM. Tool lacks idempotency hints, permission declarations, and recovery guidance.

• Expand tool description to 80-150 characters: 'Retrieve detailed BIN (Bank Identification Number) data including card brand, issuer bank, country, authentication requirements, and card features. Use this to validate card types and understand issuer capabilities.'
• Document the output schema explicitly. Describe the structure returned: card details (brand, type, prepaid, virtual), product info, bank info, country info, authentication, technical details, features, currency. Specify which fields are always present vs. optional.
• Add BIN parameter constraints: 'BIN number (6-19 digits, numeric only). Example: 411111 for Visa test cards.' Consider adding a regex pattern in the schema: '^[0-9]{6,19}$'.
• Implement error handling with actionable messages: 'BIN not found. Verify the BIN is 6-19 numeric digits.' and 'Invalid BIN format. Expected 6-19 digits, got: {input}'. Return structured error objects with error_code and recovery_hint.
• Add tool annotations: set readOnlyHint=true in the tool definition to signal this is a safe, idempotent read operation that can be retried without side effects.