Character Limit for Tool Descriptions in Tool-Bound Agents

[naveenrajusg]

openai.BadRequestError: Error code: 400 - {'error': {'message': "Invalid 'tools[0].function.description': string too long. Expected a string with maximum length 1024, but got a string with length 3817 instead.", 'type': 'invalid_request_error', 'param': 'tools[0].function.description', 'code': 'string_above_max_length'}}

I am using GPT - 4o and LangGraph framework

I get this error when i invoke ReAct agent which has tools binded to it.

I have multiple tools that are supposed to be used for a ReAct Agent, and each tool makes a call to an OpenSearch retriever. To ensure the LLM selects the correct tool, I am providing detailed descriptions of the contents each retriever holds—essentially a short description of each data folders that was ingested. However, this is causing the description length to exceed 3,000 characters. Since these descriptions are essential for preventing confusion in tool selection, I would prefer not to shorten them.

Is there a way to overcome the maximum character limit without reducing the tool descriptions?

If I move the detailed descriptions to the system prompt using the state_modifier attribute in the ReAct agent creation function, how would that differ from including the descriptions as part of the tool function in Google docstring format? As far as I understand, when tool descriptions are provided within the function using Google docstring format, they are stored as metadata in the LLM instance, making the model aware of the tool’s purpose. Would shifting them to the system prompt have the same effect, or would it impact the LLM’s ability to correctly associate tools with their intended functions?