tool_calling_tokenizer_mismatchTier 1 · 70% confidence

ai-agents-tool-calling-tokeniz-error-unexpected-token-x-while-expecting-start-tok-4a89ae40

agent: ai_agents

When does this happen?

IF Error 'Unexpected token X while expecting start token Y' during tool calling with vLLM and OpenAI-compatible clients.

How others solved it

THEN Ensure the model tokenizer includes the correct special token for tool calls (e.g., <|tool_call|>). If using a custom tokenizer, add the token and update the model config accordingly. Check vLLM issue #22519 for related discussions and potential fixes.

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