LangChain Core 1.7.0 changes streamed tool-call arguments

News AI Agent Infrastructure

  • LangChain Core 1.7.0 sends streamed tool-call arguments as `tool-call-delta` slices instead of `block-delta` snapshots.
  • Iterating over `ChatModelStream.tool_calls` now returns each call’s newly added argument slice, rather than its full accumulated arguments.
  • The behavior of `.tool_calls.get()` and `.output` is unchanged, and users who need snapshots can pin a version below 1.7.

Our take

Applications that display or log incomplete tool arguments must accumulate streamed slices to reconstruct the current state. Compared with consuming full snapshots, this adds state-management work to the stream handler; integrations using the existing accessors are unaffected.

Sources

  1. langchain-core==1.7.0 · LangChain Releases

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