### Answer Your MCP tool result is being capped because it exceeds Retell's maximum response size limit. According to the documentation, the code result is capped at 15,000 characters to prevent overloading the LLM context [(1) ]() . To fix this issue, you need to reduce the size of your MCP tool's response. Here are your options: 1. Return only essential data - Filter your response to include only the information the agent needs for the conversation, not the entire dataset. 2. Paginate or summarize - If your tool returns large datasets, implement pagination or return a summary instead of the full response. 3. Use response variables - Extract specific values from your tool response and store them as dynamic variables rather than passing the entire response to the LLM [(2) ]() . The error message "Function result too long, capping response" means Retell automatically truncated your response to fit within the 15,000 character limit, which may cause incomplete or incorrect data to reach the LLM. If you're seeing this consistently, review your MCP tool implementation to ensure it returns concise, focused data rather than verbose or complete datasets.

​ To learn more, see the sources I considered: [[1] Code Tool](https://docs.retellai.com/build/single-multi-prompt/code-tool) [[2] MCP](https://docs.retellai.com/build/single-multi-prompt/mcp) ​

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