The GDP MCP server demonstrates solid definition quality with explicit tool registration, comprehensive parameter descriptions, and tool annotations. All three tools are registered with clear names, well-documented parameters, and ToolAnnotations reflecting read-only semantics. However, there are gaps: output schemas are not formally documented (tools return strings rather than structured objects), error responses lack clear recovery guidance, and parameter constraints could be more granular. The code shows careful attention to context handling and logging, but does not fully leverage structured output patterns or multi-round-trip confirmation for consistency.

• Convert tool return types from str to structured Pydantic models (e.g. SearchResult, CategoryList, ApiDetails). Document the output schema in each tool's docstring or via FastMCP's response_schema parameter if available.
• Change 'verb' parameter in gdp_search_apis to an enum: verb: Literal['GET', 'POST', 'PUT', 'DELETE'] | None = None. This prevents hallucinated methods and is self-documenting.
• Implement structured error responses. Instead of returning JSON-in-string via _error_response(), raise exceptions with error codes, messages, and suggestions. FastMCP will serialize these correctly.
• Remove example values from parameter descriptions. Replace 'Search keyword (e.g. datasource, policy, group, ...)' with 'Search keyword for GDP API endpoints. Examples are discovered by calling gdp_list_categories.' This prevents literal reuse.
• Document result limits in gdp_search_apis description: 'Returns up to 50 matching endpoints. Use category and verb filters to narrow results.' Enforce the limit in code and document pagination if the tool grows to support it.
• For gdp_search_apis, include in the response the required_params for each endpoint as an array of strings (currently embedded in text). This enables downstream tool chaining and structured parsing.
• Add a 'suggestion' field to error responses that guides the LLM's next action: 'No endpoints matching X. Try gdp_list_categories to see available categories.' This implements the recovery-guide pattern.
• Consider splitting gdp_get_api_details into two tools: one that returns parameter schema only (for display), one that validates a proposed set of parameters before execution. This enables safer multi-step planning.

Inferred effective spec: 2026-07-28+.

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