Tool Calls Fail with g4f API in OpenCode

[marvin1099]

When invoking a tool call (bash with ls -la) through the g4f bridge (OpenAI‑compatible API) the model returns a AI_TypeValidationError. The response payload contains a tool_calls array where the index field is missing and the arguments field is an object instead of a JSON‑encoded string. This triggers a validation error:

AI_TypeValidationError: Type validation failed: Value: {"id":"chatcmpl-ALk2SMK3YYALaGE5qB03aB2J3Hxs","object":"chat.completion.chunk","created":1772454039,"model":"gpt-oss:120b","provider":"Ollama","choices":[{"index":0,"delta":{"role":"assistant","content":"","reasoning":null,"tool_calls":[{"id":"call_2c7wibf7","function":{"name":"bash","arguments":{"command":"ls -la","description":"List files in current directory","timeout":120000,"workdir":"/home/marvin"}}}]},"finish_reason":null}]}.
Error message: [{"code":"invalid_union","errors":[[{"expected":"number","code":"invalid_type","path":["choices",0,"delta","tool_calls",0,"index"],"message":"Invalid input: expected number, received undefined"},{"expected":"string","code":"invalid_type","path":["choices",0,"delta","tool_calls",0,"function","arguments"],"message":"Invalid input: expected string, received object"}],[{"expected":"object","code":"invalid_type","path":["error"],"message":"Invalid input: expected object, received undefined"}]],"path":[],"message":"Invalid input"}]

Environment

Component	Version / Details
NVIDIA provider	GPT‑OSS 120B
g4f bridge (OpenCode)	@ai-sdk/openai-compatible (npm)
Bridge base URL	http://127.0.0.1:1337/v1
Model identifier	gpt-oss-120b (mapped to g4f)
Tool definition	bash with fields command, description, timeout, workdir

Steps to Reproduce

1. Run "g4f api"

2. Configure OpenCode with the g4f bridge as shown:

   {
     "ollama": {
       "npm": "@ai-sdk/openai-compatible",
       "name": "Gf4 (bridge)",
       "options": { "baseURL": "http://127.0.0.1:1337/v1" },
       "models": {
         "gpt-oss-120b": { "name": "gpt-oss-120b" }
       }
     }
   }

3. Open opencode

4. Send a chat request that includes a tool call like "run ls"

5. in opencode i get the AI_TypeValidationError from above

Expected Behavior
The bridge should use a tool call without errors

Why
Don't know.

Impact
Tool calls cannot be used with the g4f bridge, breaking any workflow that relies on external functions (e.g., file listings, shell commands, API calls). Users see opaque validation errors instead of the expected tool execution.

Additional Notes

• The issue appears to be isolated to the g4f API implementation (error appears in opencode only).
• No errors are logged on the g4f api cli.

Reported it here first but apparently it may be a python issue.

[hlohaus]

@marvin1099 The AI omitted an index field in a section of the code. I have since updated the Ollama worker. To access unlimited NVIDIA resources, please utilize the API endpoint /api/nvidia and your API key from NVIDIA or g4f.dev.

[marvin1099]

The nvidea moddel i just used as axample here happens with all models.
Should have specified.

here as example a short history with kimi-k2-thinking over g4f ollama provider:

Please give a short awnser, for testing. 

Thinking: The user is asking for a short answer for testing purposes. This is a simple request that doesn't require any tools or complex responses. I should provide a brief, direct answer as requested.
Test response confirmed.


try if you can use ls via the bash tool

AI_TypeValidationError: Type validation failed: Value: {"id":"chatcmpl-7dMfiTtZR99rZxOi2OFhNZRnIZuO","object":"chat.completion.chunk","created":1772544196,"model":"kimi-k2-thinking","provider":"Ollama","choices":[{"index":0,"delta":{"role":"assistant","content":"","reasoning":null,"tool_calls":[{"id":"functions.bash:0","type":"function","function":{"name":"bash","arguments":"{\"command\":\"ls\",\"description\":\"List files in current directory\"}"}}]},"finish_reason":null}]}.
Error message: [{"code":"invalid_union","errors":[[{"expected":"number","code":"invalid_type","path":["choices",0,"delta","tool_calls",0,"index"],"message":"Invalid input: expected number, received undefined"}],[{"expected":"object","code":"invalid_type","path":["error"],"message":"Invalid input: expected object, received undefined"}]],"path":[],"message":"Invalid input"}]

[hlohaus]

Hello @marvin1099

I updated some more lines of code:

1448f7a#diff-e8969c4792aa5fb70ae61ba18af64ba73de1ccb2a046eba111e751ca4d540c1c

[github-actions]

Bumping this issue because it has been open for 7 days with no activity. Closing automatically in 7 days unless it becomes active again.