Task tool fails with 'Tool names must be unique' error

Description

The Task tool is failing with an API error when attempting to launch any subagent type. The error indicates that there are duplicate tool names in the configuration.

Steps to Reproduce

1. Attempt to invoke the Task tool with any subagent type
2. Example invocations that all fail:

• subagent_type: "general-purpose"
• subagent_type: "Explore"
• With or without the model parameter

Expected Behavior

The Task tool should successfully launch the specified subagent and execute the provided prompt.

Actual Behavior

All Task tool invocations fail with:

API Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"tools: Tool names must be unique."},"request_id":"req_vrtx_011CUfdJXEC1FN1xtDzaeR1m"}

Error Details

• Error Type: invalid_request_error
• Error Message: tools: Tool names must be unique.
• HTTP Status: 400
• Affected Tool: Task (all subagent types)

Environment

• Model: claude-opus-4-1@20250805
• Platform: darwin (macOS)
• Date: 2025-10-31

Impact

This prevents the use of all Task tool subagents, including:

• general-purpose
• Explore
• Plan
• code-reviewer
• test-automator
• And all other specialized agents

Workaround

Currently using direct tool invocations (Bash, Read, Write, Edit, etc.) instead of delegating to subagents.