MCP Builder Teardown: Anthropic’s first lesson in MCP Server development

If you have written MCP Server, you must have encountered this situation. Claude I had a good chat with you. You said "help me write a GitHub MCP Server", and it outputted a piece of TypeScript. It looks like that, the schema is also there, and the tool is also registered. Then you run the validator and it turns red. Not Claude does not understand the MCP specification. On the contrary, it is probably more familiar with specification documents than most human developers. The problem lies in another place: from "knowing the specifications" to "generating compliant code", there is a large section in the middle that is easily