MCP Server Scoring Methodology: How to Evaluate APIs for Agents

MCP Server Scoring Methodology: How Rhumb Evaluates API Agent-Nativeness You're building a multi-provider MCP server. You've found 5 APIs that do what you need. How do you know which one is actually safe to call unsupervised? Most developers guess. They pick the one with the best documentation or the most GitHub stars. They wire it in. Then at 3am, their agent hits a 500 with no error context, retries blindly, and creates duplicate transactions. This is why we built the Agent-Native (AN) Score. What Makes an MCP Server Reliable? When we talk about "API compatibility for MCP," we're really asking two questions: Can the agent reliably get work done? (Execution, 70% weight) Can the agent even get started? (Access, 30% weight) The first question is almost entirely ignored by existing tools. Most "API readiness" checks scan a website's metadata or robots.txt rules. Useful for AI crawlers. Useless for MCP servers. An MCP server doesn't read your landing page. It calls your endpoints. It need