openclaw - 💡(How to fix) Fix MLX LM Server tool calls fail: finish_reason 'tool_call' (singular) not recognized [1 participants]

The agent stalls because mlx_lm server returns finish_reason: "tool_call" (singular), but the mapStopReason() function in @mariozechner/pi-ai only matches "tool_calls" (plural) and "function_call". The singular form falls through to the default case and is treated as an error. return { stopReason: "error", errorMessage: Provider finish_reason: ${reason} };

Gateway Error Logs

[agent/embedded] embedded run agent end: isError=true error=Provider finish_reason: tool_call [agent/embedded] embedded run agent end: isError=true error=Provider finish_reason: tool_call [agent/embedded] embedded run agent end: isError=true error=Provider finish_reason: tool_call

TL;DR

Add a case "tool_call": to the mapStopReason() function in @mariozechner/pi-ai to handle the singular form of the finish_reason returned by mlx_lm server.

Guidance

• Apply the suggested fix by adding case "tool_call": to the mapStopReason() function in two places: node_modules/@mariozechner/pi-ai/dist/providers/openai-completions.js and dist/control-ui/assets/openai-completions-*.js.
• Verify the fix by sending a message that triggers a tool call and checking if the agent no longer errors with Provider finish_reason: tool_call.
• If modifying the node_modules directory is not desirable, consider creating a custom provider that wraps the mlx_lm server and handles the finish_reason mapping.
• Be aware that this fix may need to be reapplied if the @mariozechner/pi-ai package is updated.

Example

function mapStopReason(reason) {
    switch (reason) {
        case "function_call":
        case "tool_call":        // ← add singular form
        case "tool_calls":
            return { stopReason: "toolUse" };
        // ...
        default:
            return { stopReason: "error", errorMessage: `Provider finish_reason: ${reason}` };
    }
}

Notes

This fix assumes that the mlx_lm server will always return either "tool_call" or "tool_calls" as the finish_reason. If other variations are possible, additional cases may need to be added to the mapStopReason() function.

Recommendation

Apply the workaround by adding the case "tool_call": to the mapStopReason() function, as this is a targeted fix that addresses the specific issue with the mlx_lm server returning a singular finish_reason.