How a Google Maps API Format Change Broke a LangGraph Agent Into an Infinite Loop

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A developer team's LangGraph-based agentic AI system failed after the Google Maps API unexpectedly changed its response format, causing an MCP Tool primitive to crash repeatedly. Because the primitive lacked error handling, the LangGraph agent could not parse the new response and entered an infinite loop with no recovery path. The team conducted a postmortem and identified that hardcoded assumptions about API response structures were the root cause of the fragility. To fix the issue, they added try-except blocks to the primitive and used LangGraph's add_conditional_edges method to route the agent toward an error-handling node when a failure occurs. The writeup serves as a practical guide for building more resilient agentic AI systems that can gracefully handle third-party API changes.

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