[BUG] webfetch tool schema missing required 'format' parameter #6288

Description

The webfetch tool schema exposed to LLMs is missing the required format parameter. When the LLM calls webfetch without specifying format, the tool fails with a validation error.

Error message:

Invalid option: expected one of "text"|"markdown"|"html"

Root cause:
The tool definition in webfetch.ts defines format as a required parameter:

format: z.enum(["text", "markdown", "html"])
  .describe("The format to return the content in")

However, the schema exposed to the LLM only includes:

• url (required)
• timeout (optional)

The format parameter is missing from the schema definition given to the model.

OpenCode version

1.0.204

Steps to reproduce

1. Start OpenCode
2. Ask it to fetch a URL (e.g., "fetch https://opencode.ai/docs")
3. Observe the validation error about missing format parameter

Operating System

macOS

Terminal

Ghostty