If an MCP server is usually a thin layer over an API, the practical takeaway is simple: treat the API contract as the th...

If an MCP server is usually a thin layer over an API, the practical takeaway is simple: treat the API contract as the thing that can actually break you.A useful method is to review changes in this order:API surface: endpoints, required params, response fields, enums, auth shapeMCP mapping: which API fields become tool inputs/outputsAgent behavior: prompts, tool choice, retry logic, and error handlingThat order matters because MCP can make an integration look stable while the underlying API has already shifted. A renamed field, a newly required parameter, or an enum value removal may not show up as an obvious MCP problem at first. It often lands later as vague tool failure, bad completions, or agents taking the wrong branch.The solid DIY baseline is enough for many teams: keep an OpenAPI spec, diff it in CI, and manually classify changes as breaking or non-breaking before updating the MCP wrapper. If your API is small and the tool surface is narrow, that can be perfectly sufficient.The ...