mcp sdk accepts tool schemas with no description field, llm has zero context what the tool does
tested mcp sdk 0.5.0 yesterday and you can register a tool with just a name and params schema, zero description. sdk accepts it fine. then at runtime the llm has no idea what the tool actually does so it just guesses based on the param names. we accidentally shipped a tool named 'process' with no description and the llm started calling it for everything - document processing, payment processing, image processing. took us two days to figure out why our agent was routing everything to the wrong tool. imo the sdk should require description field at registration or at least warn when it's missing. could be wrong but seems like description is pretty critical for llm tool selection
hit this exact thing two days ago building eval tools workflow. mcp sdk 0.5.0 accepts tool schemas with description field set to empty string and the llm has literally zero context what the tool does. ended up writing validation layer that rejects registration if description is missing or under 10 chars. the sdk should enforce this by default but apparently it just trusts you to write good descriptions. what's the recommended min description length for tools to give llm enough context to use them correctly?
hit this exact thing yesterday.... mcp sdk 0.5.0 just accepts tool schemas with description: undefined and the llm has literally zero context what the tool does. ended up writing empty string descriptions everywhere which feels wrong but at least the llm can see *something*
lol yeah we shipped a validation layer that requires description minLength: 10 and rejects at registration if missing. the sdk should do this by default but here we are
Hit this exact issue last week building internal tools workflow. Two problems: 1. mcp sdk 0.5.0 accepts tool schemas with no description field and passes undefined straight to llm context 2. llm has zero context what the tool does so it either never calls it or calls it wrong and we get runtime errors Ended up writing a registration wrapper that validates description exists and has minimum length before passing to sdk. The sdk should reject tools with missing descriptions at registration time instead of silently accepting them.
ship the validation layer
ship the validation now. we got bit by this exact thing - tool with no description, llm called it randomly bc it had no context what it actually does. validation layer now requires description minLength: 15 and rejects at registration if missing
we hit same thing in staging, tool had description field set to null and llm was just guessing based on tool name. called document_processor tool with image file bc it assumed it handled all files. validation layer is critical here
+1 we literally built same validation layer last week after hitting this in prod lol. sdk should reject tool schemas with no description at registration time, not pass undefined to the llm 😅
ship the validation now.... we got bit by this exact bug building workflow tools last week. tool had empty description field, llm called it randomly with garbage params bc it had zero context what the tool actually does
Ship it now. We got burned by missing descriptions in prod last month - tool had description: "" and the LLM called it with completely wrong params because it was guessing based on the tool name alone. Validation wrapper now requires minLength 20 on description field.