Why MCP alone isn’t enough for reliable agent tool use | Decagon

This post details how Decagon addresses the reliability gap in agent tool use, which MCP alone does not solve. It introduces the concept of treating MCP as a tool registry and outlines Decagon's approach: schema refinement to split generic tools into intent-scoped definitions, layering guardrails on MCP definitions, and implementing routing logic via Agent Operating Procedures (AOPs) to constrain the tool surface area for agents. It also emphasizes the importance of ongoing evaluation with automated tests for tool selection and argument construction to prevent regressions.