[Bug]: `tool_call` error, only in grok-3-mini

[Manamama]

Bug Description

I use gemini that is Gemini CLI a lot. I have decided to test your grok one.

The below worked with the default Grok model (no model given), but with
export GROK_MODEL=grok-3-mini

it fails with:

Type your request in natural language. Ctrl+C to clear, 'exit' to quit.


  > Reread GROK.md then. If needed, also other files, but I reckon not needed by now.

  ⏺ Read(GROK.md)
    ⎿ File contents:
      Contents of GROK.md:
      1: Grok, here is the dump of our chat so far, as session broke: 
      2: 
      3: 
      4:   > Very good. This repo has files. Do this: 1. Check the files. 2. Check the `git` status and history (shortly). 3. Read `GEMINI.md` file's content here 4. Report what you understand. 
      5: 
      6:   ⏺ Created Todo
      7:     ⎿ ○ List the files in the current directory using bash 'ls -la'
      8:       ○ Check git status using bash 'git status' and short history with 'git log --oneline -n 5'
      9:       ○ View the content of GEMINI.md using view_file
      10:       ○ Summarize understanding of the repo based on gathered information
      ... +242 lines

  ⏺ Function: You have successfully viewed the contents of GROK.md. Here's the output:

    Contents of GROK.md:
    1: Grok, here is the dump of our chat so far, as session broke: 
    2: 
    3: 
    4:   > Very good. This repo has files. Do this: 1. Check the files. 2. Check the git status and history (shortly). 3. Read GEMINI.md file's content here 4. Report what you understand. 
    5: 
    6:   ⏺ Created Todo
    7:     ⎿ ○ List the files in the current directory using bash 'ls -la'
    8:       ○ Check git status using bash 'git status' and short history with 'git log --oneline -n 5'
    9:       ○ View the content of GEMINI.md using view_file
    10:       ○ Summarize understanding of the repo based on gathered information
    ... +242 lines

  > Never output content of files! Now go on with the task. 

  ⏺ This task involves multiple steps based on the instructions in GROK.md. To proceed efficiently, I'll create a todo list to plan and track the tasks.

  ⏺ Created Todo
    ⎿ ○ List the files in the current directory using bash 'ls -la'
      ○ Check git status using bash 'git status' and short history with 'git log --oneline -n 5'
      ○ View the content of GEMINI.md using view_file (without outputting contents)
      ○ Summarize understanding of the repo based on gathered information


  ⏺ Updated Todo
    ⎿ Executing...

  ⏺ Sorry, I encountered an error: Grok API error: 400 "Invalid request content: The arguments to a tool_call are not a valid JSON string. Parsing error: Error("trailing characters", line: 1, column: 52)"

Restarting does not help.

Grok online advises below, but I cannot be bothered to look into grok's code and do A/B testing. For the record only:

4. Recommendations

Fixing the Grok CLI Error:

Enable debug mode (if available) to inspect the JSON payload: grok --debug ....
Test individual commands (e.g., grok --prompt "Run ls -la") to isolate the failing tool call.
Update Grok CLI: npm update -g @vibe-kit/grok-cli.
If the error persists, use the cURL command with task.json to bypass CLI issues.

Using Grok CLI for Repository Tasks:

Install Grok CLI if not already done: npm install -g @vibe-kit/grok-cli.
Run the consolidated prompt above or split tasks for clarity:
bashgrok --model grok-4-latest --prompt "Run ls -la"
grok --model grok-4-latest --prompt "Run git status && git log --oneline -n 5"
grok --model grok-4-latest --prompt "Summarize the repository's purpose based on GEMINI.md (Gemini CLI docs) and red_spiral.py (spiral pattern script)"
...

Steps to reproduce

No response