opencode-strip-empty-params-plugin

An opencode plugin that strips empty-string values from non-required MCP tool-call arguments before the call reaches the server.

Problem

Some LLMs (notably OpenAI GPT-family models) always emit every JSON key defined in a tool's input schema, filling optional parameters with empty strings, zeros, or false even when no value was intended.

Several MCP servers treat "" differently from an absent key. For example, Slack's MCP server returns zero results when cursor: "" is passed, even though omitting cursor entirely works correctly. This makes the same MCP tool work with one model family and silently fail with another.

How it works

The plugin hooks tool.execute.before and, for each MCP tool call, removes any argument whose value is "" and whose key is not in the tool schema's required array.

Required parameters are never touched so genuine validation errors still surface.

Installation

# in opencode.json

{
  "plugin": [
    "opencode-strip-empty-params-plugin"
    // or with options:
    // ["opencode-strip-empty-params-plugin", { "scope": "all", "verbose": true }]
  ]
}

Options

| Option | Type | Default | Description | |-----------|---------------------|---------|------------------------------------------------| | scope | "mcp" | "all" | "mcp" | Which tools to apply to | | verbose | boolean | false | Log each stripped key to stderr for debugging |

Links

• npm package
• GitHub repository
• opencode plugin docs

Publishing

npm login     # one-time, opens browser to authenticate with npmjs.org
npm publish

The package is unscoped so it publishes as public by default. Bump the version in package.json before each release.

License

MIT