zed-industries/zed · error · LanguageModelCompletionError

Stream ended without receiving a complete tool use

Error message

Stream ended without receiving a complete tool use

What it means

Raised in stream_completion_tool after draining the entire completion event stream: no event carried a ToolUse with is_input_complete (complete tool inputs), yet the caller expected the model to invoke a tool. The model ended its turn with plain text, a stop, or an incomplete tool use instead of delivering a finished tool call, so the tool-use contract of the request was violated.

Source

Thrown at crates/language_model/src/language_model.rs:301

            let mut events = events.fuse();

            // Iterate through events until we find a complete ToolUse
            while let Some(event) = events.next().await {
                match event {
                    Ok(LanguageModelCompletionEvent::ToolUse(tool_use))
                        if tool_use.is_input_complete =>
                    {
                        return Ok(tool_use);
                    }
                    Err(err) => {
                        return Err(err);
                    }
                    _ => {}
                }
            }

            // Stream ended without a complete tool use
            Err(LanguageModelCompletionError::Other(anyhow::anyhow!(
                "Stream ended without receiving a complete tool use"
            )))
        }
        .boxed()
    }

    #[cfg(any(test, feature = "test-support"))]
    fn as_fake(&self) -> &fake_provider::FakeLanguageModel {
        unimplemented!()
    }
}

impl std::fmt::Debug for dyn LanguageModel {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("<dyn LanguageModel>")
            .field("id", &self.id())
            .field("name", &self.name())
            .field("provider_id", &self.provider_id())

View on GitHub (pinned to f4178619ac)

Solutions

1. Retry the request — models occasionally omit the expected tool call
2. Check that the request actually requires a tool (tool_choice forced) and the tools are correctly advertised
3. Inspect the stream events for incomplete ToolUse chunks or a Stop reason explaining the early end
4. Reduce prompt complexity or max_tokens constraints that may end the turn before the tool call completes

When it happens

Trigger: Thrown at crates/language_model/src/language_model.rs:301 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of zed-industries/zed@f4178619ac (2026-08-20). Data as JSON: /api/errors/f3a63c6fc4bef06c. Report an issue: GitHub.