Gemma 4 (e4b) tool calling fails via Ollama OpenAI-compatible API — streaming tool_calls not recognized

[noxgle]

Description

Gemma 4 (e4b) tool calling fails via Ollama OpenAI-compatible API — streaming tool_calls not recognized

Summary

When using Gemma 4 (e4b) via Ollama (ollama/gemma4:e4b) as a provider, the model correctly returns tool_calls in the response, but OpenCode does not recognize them and the model responds with "I do not have the capability to execute system commands" instead of calling tools.

Reproduction

1. Configure Ollama as a provider in opencode.json:

{
  "provider": {
    "ollama": {
      "npm": "@ai-sdk/openai-compatible",
      "name": "Ollama",
      "options": {
        "baseURL": "http://localhost:11434/v1"
      },
      "models": {
        "gemma4:e4b": {
          "name": "Gemma 4 e4b",
          "tools": true,
          "limit": {
            "context": 128000,
            "output": 8192
          }
        }
      }
    }
  }
}

2. Run opencode -m ollama/gemma4:e4b
3. Ask: "list files in /tmp"

Expected behavior

The model should call the bash tool with ls /tmp.

Actual behavior

The model responds with: "I do not have the capability to execute system commands like listing directory contents."

Root cause analysis

I investigated and found that:

1. Ollama API works correctly — both native (/api/chat) and OpenAI-compatible (/v1/chat/completions) endpoints return proper tool_calls with finish_reason: "tool_calls" for gemma4.
2. Streaming also works at the API level — The streaming response includes tool_calls in the delta and ends with finish_reason: "tool_calls".
3. The issue is on the opencode side — The AI SDK (@ai-sdk/openai-compatible) or opencode is not properly parsing/recognizing the tool calls from gemma4 in streaming mode.

API verification

Non-streaming (works):

curl -s http://localhost:11434/v1/chat/completions -d '{
  "model": "gemma4:e4b",
  "messages": [{"role": "user", "content": "list files in /tmp"}],
  "stream": false,
  "tools": [{"type": "function", "function": {"name": "bash", "description": "Execute a shell command", "parameters": {"type": "object", "required": ["command"], "properties": {"command": {"type": "string"}}}}}]
}'
# Returns: finish_reason: "tool_calls", tool_calls: [{function: {name: "bash", arguments: "{\"command\":\"ls /tmp\"}"}}]

Streaming (also works at API level):

# Streaming includes tool_calls in delta and finish_reason: "tool_calls" in final chunk

Environment

• OpenCode version: 1.3.13
• Ollama version: 0.20.2 (Docker)
• Model: gemma4:e4b
• OS: Linux

Workaround

Using qwen3.5:9b works correctly with tool calling. The issue is specific to gemma4.

Related

• ollama/ollama#15241 — Gemma4 tool call parsing fixed in Ollama 0.20.2
• PR #16531 — OpenAI-compatible custom tool compat layer (unmerged)
• Issue #20669 — Default agent brittle against local tool-call quirks
• PR #15306 — Ollama-side tool calling rework for Gemma4

Suggested fix

The toolParser compat layer from PR #16531 should be merged to handle gemma4 tool call format differences, particularly in streaming mod

Plugins

No response

OpenCode version

No response

Steps to reproduce

No response

Screenshot and/or share link

No response

Operating System

No response

Terminal

No response

[LohanGuedes]

Somehow this actually works with gemma4:e4b if you use @ then explicitly say "this current folder"

I don't know if this is something regarding the model, but seems to me that gemma4 is just dumb...

EDIT: fun enough qwen3.5:9b didn't work in my case.

[noxgle]

This model gemma 4:e4b is for edge devices, but such simply job like "show files " should work.

[A-Risoli]

On Ubuntu :

ollama launch claude --model gemma4:26b

/init

● I apologize, but I cannot execute system commands directly through a bash tool as it is not available in my current environment.

Same scenario using Codex :

ollama launch codex --model gemma4:26b

/init

I am sorry, but I cannot execute shell commands directly. I am an AI model designed to process and generate text and code.

If you have a specific command you are trying to run or a script you need help writing, please provide the details, and I will be happy to help you debug, explain, or write the code for it!

[jazzista88]

Same issue here with opencode, i would use gemma4 as coder executor, no thinking or planning.
Is there already a fix on this ?