[BUG] Claude fails to invoke Skills immediately despite explicit instructions

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

Claude Code is not following the documented behavior for Skills invocation. According to the Skill tool instructions, when a skill is relevant, Claude must "invoke this tool IMMEDIATELY as your first action" - this is described as a "BLOCKING REQUIREMENT."

What Should Happen?

According to the Skill tool instructions:

• "When a skill is relevant, you must invoke this tool IMMEDIATELY as your first action"
• "This is a BLOCKING REQUIREMENT: invoke the relevant Skill tool BEFORE generating any other response about the task"

Claude should immediately invoke the relevant Skill tool as the very first action when a user request clearly matches an available skill's description.

Error Messages/Logs

Steps to Reproduce

1. Have a custom skill configured
2. Make a request that clearly matches the skill's description
3. Observe that Claude performs other exploratory actions instead of invoking the skill immediately

Observed Behavior

When asked to "run in a Gitlab campaign all tests from testing campaigns: campaign_A, campaign_B", which directly matches the test-pipeline-starter skill description ("run tests, obtained from a failing pipeline or a custom list, via Gitlab pipeline"), Claude instead:

1. Started with exploratory Glob searches for campaign files
2. Searched for digital test configuration files
3. Attempted to find GitLab CI configuration files
4. Only invoked the skill after being interrupted and questioned multiple times

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.0.70

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_