vllm - 💡(How to fix) Fix [Bug] DeepSeek V4 tool calling returns boolean parameters as quoted strings which causes subagent failed in ClaudeCode [1 participants]

TL;DR

The issue can be fixed by modifying the DeepSeekV32ToolParser to correctly parse boolean parameters from JSON strings to JSON booleans.

Guidance

• Verify that the DeepSeekV32ToolParser is correctly configured to handle boolean parameters in non-streaming mode.
• Check the tool schema declaration for the run_in_background parameter to ensure it is set to boolean.
• Consider adding a custom parsing logic to the DeepSeekV32ToolParser to convert JSON string booleans to JSON booleans.
• Test the fix by deploying DeepSeek V4 with vLLM and using the messages endpoint for ClaudeCode calling subagent.

Example

// Expected output
{"run_in_background": true,...}

// Current output
{"run_in_background": "true",...}

A potential fix could involve modifying the DeepSeekV32ToolParser to use a custom JSON deserializer that converts string booleans to boolean values.

Notes

The issue seems to be specific to the DeepSeekV32ToolParser and non-streaming mode. The fix may not apply to other parsers or modes.

Recommendation

Apply a workaround by modifying the DeepSeekV32ToolParser to correctly parse boolean parameters, as upgrading to a fixed version is not mentioned in the issue.