CLAUDE_CODE_AGENT

Updated October 13, 2026 by Alex Sorokoletov

CLAUDE_CODE_AGENT is a Claude Code environment variable: Full agent descriptor passed into a spawned agent process — likely the agent's frontmatter (tools, allowed/disallowed lists, system prompt path) so the child can reconstruct its runtime without re-reading disk. Added between v2.1.118 and v2.1.123 and still present in v2.1.294. 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_CODE_AGENT=<value>
claude

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

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

Release notes that mention it

• Claude Code v2.1.123 — Background Daemons, Agent Fleets, and CoWork Memory

Related variables

• CLAUDE_AGENT: Short-form identifier for the current agent, used in inter-agent messaging and log attribution.
• CLAUDE_AGENT_SDK_CLIENT_APP: Client application name.
• CLAUDE_AGENT_SDK_DISABLE_BUILTIN_AGENTS: Disable built-in agent types.
• CLAUDE_AGENT_SDK_MCP_NO_PREFIX: Don't prefix MCP tool names with server name.
• CLAUDE_AGENT_SDK_VERSION: Agent SDK version sent in User-Agent header.
• CLAUDE_CODE_AGENT_COST_STEER: Controls cost-aware behavior for subagent delegation.
• CLAUDE_CODE_AGENT_LIST_IN_MESSAGES: An early agent-listing toggle, made obsolete by the Agent View and coordinator surfaces that now own how agents are shown.
• CLAUDE_CODE_AGENT_RULE_DISABLED: Disable agent rules.

Frequently asked questions

All variables, searchable: Claude Code environment variables.