Tool calls result in JSON parsing error - parameters duplicated #17315

Description

version 1.2.25
I use self-model (ZhipuAI/GLM-5-FP8) tool calls fail with a JSON parsing error. The parameters appear to be duplicated in the JSON payload.
Error Example:
Invalid input for tool bash: JSON parsing failed:
Text: {"command":"pwd","description":"Check current directory"{"command": "pwd", "description": "Check current directory"}.
Error message: JSON Parse error: Expected '}'
Expected JSON:
{"command":"pwd","description":"Check current directory"}
Actual JSON (what I'm seeing):
{"command":"pwd","description":"Check current directory"{"command": "pwd", "description": "Check current directory"}
Observations:

1. The read tool worked successfully at the beginning of the conversation
2. After several tool calls, tools like bash, edit, glob, w

rite started failing
3. The JSON parameters are being duplicated/concatenated incorrectly
4. Other models (e.g., Claude, GPT) do not have this issue with the same opencode version
Environment:

• Model: vllm-local/yhglm5
• Platform: darwin
• Opencode version: (latest)
  Steps to Reproduce:

1. Start a conversation with yhglm5 model
2. Make several tool calls (read, bash, edit, etc.)
3. After some point, tool calls will fail with the duplicated JSON error

Plugins

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OpenCode version

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Steps to reproduce

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Screenshot and/or share link

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Operating System

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Terminal

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