This MCP Auth PoC server demonstrates a foundational proof-of-concept with clear separation of concerns and basic patterns established. All three tools are explicitly defined in tools.py with verb-based names and descriptions. However, the implementation has significant gaps: no input schema validation visible in the actual tool registrations, parameter types are inferred from function signatures rather than declared in JSON Schema, output schemas are undocumented, and error handling is minimal. The code contains useful patterns and comments, but these do not compensate for missing schema rigor in the registration layer. Tool descriptions are adequate (100-150 chars) but lack the structured guidance on when to use each tool and what downstream operations are possible. No tool annotations (readOnly/destructive/idempotent hints) are present. The tools are simple and single-purpose (good composition), but lack the production-grade schema completeness expected for a 70+ score.

• Explicitly define JSON Schema for each tool's input parameters in the server registration. For tool_get_greeting, declare { 'type': 'object', 'properties': { 'name': { 'type': 'string', 'description': 'Optional name to greet (default: "there")', 'minLength': 1, 'maxLength': 100 } }, 'required': [] }.
• Document output schemas for each tool. Example for tool_echo_message: 'Returns a JSON object with fields: original_message (string), echoed_at (ISO 8601 timestamp), user (object with username, user_id, role), message_length (integer).'
• Add tool annotations to the FastMCP registration: mark all three tools with readOnlyHint: true since they only query data.
• Implement defensive error handling in each tool. Example: wrap context.request.state.user access in a try-except and return { 'error': 'unauthenticated', 'message': 'User context not available. Verify authentication middleware is active.' } if user is missing.
• Enhance tool descriptions with guidance on when to use each tool. Example for tool_get_greeting: 'Retrieve a personalized greeting for the currently authenticated user. Use this to confirm identity and establish context. Returns user's username, ID, and role.'
• Add input validation examples to the actual tool implementations (not just docstrings). For tool_echo_message, validate that message is non-empty and reasonably sized (e.g., < 10,000 chars) before echoing.
• Include downstream reference fields in responses. For tool_get_user_stats, document that it returns user_id and username so agents can chain to other user-specific tools (if they exist in the full system).