OpenCode plus Zen Gemini 3 Pro model causes errors

[rheckart]

Description

I was using the BMAD Method templates with an older version of OpenCode, Zen Gemini 3 model and it was working fine. Upgrading to version 106 is now causing these issues with Gemini specifically:

* GenerateContentRequest.tools[0].function_declarations[11].parameters.properties[truncateMode].enum: only allowed for STRING type
* GenerateContentRequest.tools[0].function_declarations[23].parameters.properties[truncateMode].enum: only allowed for STRING type
* GenerateContentRequest.tools[0].function_declarations[29].parameters.properties[truncateMode].enum: only allowed for STRING type
* GenerateContentRequest.tools[0].function_declarations[31].parameters.properties[severityFilter].items.enum: only allowed for STRING type

Switching to another Zen model like Claude Sonnet 4.5 resolves the issue.

OpenCode version

1.0.106

Steps to reproduce

1. Install the BMAD tools into an empty folder,
2. Run OpenCode, choosing Zen Gemini 3 Pro as the model,
3. Try a custom command like /bmad-workflow-bmm-workflow-status and the errors occur,
4. Change the model to Zen Claude Sonnet 4.5,
5. Run the same custom command and the command completes as expected.

Screenshot and/or share link

No response

Operating System

Omarchy Arch Linux

Terminal

Ghostty

[rekram1-node]

There is an mcp server causing this issue looks like?

[rekram1-node]

Will fix tho

[rheckart]

There is an mcp server causing this issue looks like?

Could be? I only have two:

{
  "$schema": "https://opencode.ai/config.json",
  // Theme configuration
  "theme": "aura",
  "model": "anthropic/claude-sonnet-4-5",
  "autoupdate": true,
  "mcp": {
    "rider": {
      "type": "remote",
      "url": "http://localhost:64342/sse",
      "headers": {
        "IJ_MCP_SERVER_PROJECT_PATH": ""
      }
    },
    "context7": {
      "type": "remote",
      "url": "https://mcp.context7.com/mcp",
      "headers": {
        "CONTEXT7_API_KEY": "ctx7sk-..."
      }
    }
  }
}

[rekram1-node]

the rider mcp has invalid tools, someone has a pr addressing at least part of this that ill merge in to fix tho

for now u can disable the mcp server

basically we have to edit the tools to translate them depending on what provider u are using

[rekram1-node]

because by default it has tools that gemini cant use