This MCP server exposes only a single tool (add_numbers) with minimal real-world utility. The tool has a basic description and input schema, but lacks critical production patterns: no error handling guidance, no output schema documentation, no pagination (where applicable), no idempotency guarantees, and no security considerations. The server itself is an OAuth gateway (per the repo name and visible code), but the MCP tool exposed does not reflect that functionality, it appears to be a trivial demo tool. The codebase shows a Next.js/Express-based OAuth implementation with database integration (Drizzle ORM, PostgreSQL), but the MCP layer is superficial. The tool definition exists but the implementation does not meaningfully integrate the OAuth functionality that the server was built for.

• Replace 'add_numbers' with actual OAuth tools: register_oauth_client (accept client_name, redirect_uris; return client_id, client_secret), get_oauth_token (accept grant_type, code, redirect_uri, client_id; return access_token, expires_in), revoke_oauth_token (accept token, client_id; return success status). These align with the server's actual functionality.
• For each OAuth tool, add a full description (100-200 chars) explaining WHAT it does, WHEN to use it (e.g. 'Call register_oauth_client first to set up a new client, then use get_oauth_token to exchange an auth code for credentials'), and any prerequisites.
• Document output schemas for every tool. E.g. register_oauth_client returns {client_id: string, client_secret: string, redirect_uris: string[]}; get_oauth_token returns {access_token: string, token_type: 'Bearer', expires_in: number}.
• Add error handling guidance to each tool. E.g. 'If register_oauth_client returns 400, the client_name was missing, retry with a valid name. If 500, the database is unavailable, wait and retry.'
• Add tool annotations: mark get_oauth_token as idempotent (same code+client_id produces same token); mark register_oauth_client as destructive (creates persistent records); mark token revocation as irreversible.
• Validate numeric inputs on add_numbers: if retaining this tool, add constraints like min/max values or handling for special values (NaN, Infinity), with error guidance if violated.
• Expose user authentication/authorization context to MCP tools. The OAuth server already uses better-auth; ensure MCP tool calls include the authenticated user's scope/permissions so tools can enforce least-privilege access.