CLAUDE_API_SKILL_DESCRIPTION

Updated October 13, 2026 by Alex Sorokoletov

CLAUDE_API_SKILL_DESCRIPTION is a Claude Code environment variable: Registration hook for the built-in "claude-api" skill that bundles Anthropic SDK docs (Python, TypeScript, Java, Go, Ruby, PHP, C#, curl) plus shared references on models, prompt caching, managed agents, and tool use. Overrides the default skill description. Removed between v2.1.247 and v2.1.252, so current releases ignore it. It is not in the official reference.

How to set it

For one session, export it in the shell that starts Claude Code:

export CLAUDE_API_SKILL_DESCRIPTION=<value>
claude

To apply it to every session, add it to the env object of a settings file:

// ~/.claude/settings.json
{
  "env": {
    "CLAUDE_API_SKILL_DESCRIPTION": "<value>"
  }
}

Release notes that mention it

• Claude Code v2.1.114 — Native Binary Launcher, /fewer-permission-prompts, and 20 New Environment Variables
• Claude Code v2.1.108 — 4 New Environment Variables: REPL Variants, Skill Discovery, and the Limits Reckoning
• Claude Code Version Tracker: Undocumented Env Vars, Feature Gates & Models

Related variables

• CLAUDE_CODE_DISABLE_CLAUDE_API_SKILL: Disables the built-in Claude API skill.
• CLAUDE_CODE_SKILL_DESCRIPTION
• CLAUDE_CODE_HOST_SKILL_CATALOG: A JSON object ({"skills": [...]}) of 1 to 64 folder names that scopes which synced claude.ai skills a remote session loads.
• CLAUDE_CODE_DESKTOP_SKILL_SWITCHES
• CLAUDE_CODE_DISABLE_CLAUDE_CODE_SKILL
• CLAUDE_CODE_SKILL_ATTRIBUTION
• CLAUDE_CODE_SKILL_DESC_REFRAME
• CLAUDE_CODE_SKILL_NAME

Frequently asked questions

All variables, searchable: Claude Code environment variables.