[BUG] Agent exists but not recognized as Skill - fails silently then executes manually

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Description:

Bug Summary
When an Agent is defined in .claude/agents/, Claude attempts to invoke it as a Skill but fails to find it, then proceeds to execute the task manually instead of using the agent.

Actual Behavior
Claude says something like:
"I'll use the 'A Agent' skill... Oh, that skill doesn't exist. Let me do it manually."

Then proceeds without using the defined agent.

Environment

• Claude Code CLI
• Custom agents defined in .claude/agents/

What Should Happen?

Expected Behavior

• Agent defined in .claude/agents/ should be invoked via the Task tool with subagent_type parameter
• OR if using Skill tool, it should correctly recognize agents vs skills

Error Messages/Logs

Steps to Reproduce

Steps to Reproduce

1. Define a custom agent in .claude/agents/
2. Ask Claude to perform a task that should trigger that agent
3. Observe Claude attempting to use Skill tool instead of Task tool

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.6

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

iTerm2

Additional Information

_No response_