{"record":{"id":"999430d1fcf7cfde","repo":"rohitg00/ai-engineering-from-scratch","slug":"each-tool-descriptor-requires-a-non-empty-descript","errorCode":null,"errorMessage":"each tool descriptor requires a non-empty description","messagePattern":"each tool descriptor requires a non-empty description","errorType":"validation","errorClass":"ProtocolViolation","httpStatus":null,"severity":"error","filePath":"phases/13-tools-and-protocols/31-mcp-conformance-versioning-and-operations/code/main.py","lineNumber":278,"sourceCode":"        if result_type != \"complete\":\n            raise ProtocolViolation(\"tools/list must return a complete result\")\n        tools = result.get(\"tools\")\n        if not isinstance(tools, list):\n            raise ProtocolViolation(\"complete tools/list result requires a tools array\")\n        names: set[str] = set()\n        for tool in tools:\n            if not isinstance(tool, dict):\n                raise ProtocolViolation(\"each tools/list descriptor must be an object\")\n            name = tool.get(\"name\")\n            description = tool.get(\"description\")\n            input_schema = tool.get(\"inputSchema\")\n            if not isinstance(name, str) or not name:\n                raise ProtocolViolation(\"each tool descriptor requires a non-empty name\")\n            if name in names:\n                raise ProtocolViolation(\"tools/list contains a duplicate tool name\")\n            names.add(name)\n            if not isinstance(description, str) or not description:\n                raise ProtocolViolation(\"each tool descriptor requires a non-empty description\")\n            if not isinstance(input_schema, dict) or input_schema.get(\"type\") != \"object\":\n                raise ProtocolViolation(\"each tool descriptor requires an object-root inputSchema\")\n\n    if method == \"completion/complete\":\n        if result_type != \"complete\":\n            raise ProtocolViolation(\"completion/complete must return a complete result\")\n        completion = result.get(\"completion\")\n        if not isinstance(completion, dict):\n            raise ProtocolViolation(\"completion/complete requires a completion object\")\n        values = completion.get(\"values\")\n        if not isinstance(values, list) or any(not isinstance(value, str) for value in values):\n            raise ProtocolViolation(\"completion.values must be an array of strings\")\n        if len(values) > 100:\n            raise ProtocolViolation(\"completion.values must contain at most 100 entries\")\n        total = completion.get(\"total\")\n        if total is not None and (\n            isinstance(total, bool) or not isinstance(total, int) or total < len(values)\n        ):","sourceCodeStart":260,"sourceCodeEnd":296,"githubUrl":"https://github.com/rohitg00/ai-engineering-from-scratch/blob/39ea8a1c6d0b61f071226eff7ede4d4105fed820/phases/13-tools-and-protocols/31-mcp-conformance-versioning-and-operations/code/main.py#L260-L296","documentation":"Error \"each tool descriptor requires a non-empty description\" thrown in rohitg00/ai-engineering-from-scratch.","triggerScenarios":"Thrown at phases/13-tools-and-protocols/31-mcp-conformance-versioning-and-operations/code/main.py:278 when the library encounters an invalid state.","commonSituations":"See trigger scenarios.","solutions":[],"exampleFix":null,"handlingStrategy":null,"validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"analyzedSha":"39ea8a1c6d0b61f071226eff7ede4d4105fed820","analyzedAt":"2026-08-26T03:13:46.626Z","schemaVersion":2},"datasetVersion":"2026-08-26T07:17:17.940Z"}