Community Answers

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Answered questions carry a ✅ in Q&A. This page is the human-curated layer on top: grouped by what you are actually trying to do.

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The loop and tools

Question	Short answer
Why does my agent call the same tool twice?	You appended the tool result but not the assistant message that requested it. From the model's side it never asked. Append the assistant message verbatim first
Why is [] more dangerous than an exception?	An exception cannot be misread as data. [] reads as "nothing applies" when it means "I found nothing". Return an explicit status. TOOL-03
Why does except Exception not catch everything?	SystemExit and KeyboardInterrupt inherit from BaseException. In a dispatcher, except BaseException is correct — it is a boundary

Bedrock and AWS

Question	Short answer
What does ValidationException on the model ID mean?	You passed a bare model ID where an inference profile ID is required. aws bedrock list-inference-profiles
What will this cost me?	Inference is cheap; idle OpenSearch collections and AgentCore runtimes are not. Tear down as you go
Why does access fail only sometimes?	A geographic inference profile routes across regions. You need model access in every destination

Frameworks

Question	Short answer
Strands or LangChain first?	Neither — learn the loop first. Then whichever your codebase uses, which for most people is LangChain

Retrieval and evaluation

Question	Short answer
My citation does not support the claim. What are we measuring wrong?	Citation theatre. Retrieved ≠ cited ≠ verified; you are measuring the first two. Spot-check five per release
How do I know if my golden set is any good?	How many cases did it fail the day you froze it? If almost none, it is a mirror

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