CLAUDE_CODE_SUBAGENT_MODEL

Updated October 13, 2026 by Alex Sorokoletov

CLAUDE_CODE_SUBAGENT_MODEL is a Claude Code environment variable: Force a specific model for sub-agent operations. Present since v2.1.69 or earlier and still present in v2.1.294. It is listed in the official reference.

How to set it

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

export CLAUDE_CODE_SUBAGENT_MODEL=<value>
claude

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

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

Release notes that mention it

• Claude Code v2.1.85 — 6 New Environment Variables: MCP Server Config and a 7 MB Diet
• Claude Code v2.1.84 — 6 New Environment Variables: Idle Management and Stream Resilience
• 83 Undocumented Claude Code Environment Variables (v2.1.19)

Related variables

• CLAUDE_CODE_SUBAGENT_MODEL_FORCE
• CLAUDE_CODE_ENABLE_APPEND_SUBAGENT_PROMPT: Authorizes SDK callers to append a custom string to a subagent's system prompt via options.appendSubagentSystemPrompt.
• CLAUDE_CODE_FORK_SUBAGENT: Changelog-confirmed[1]: set to 1 to run subagents as forked processes (v2.1.117 on external builds, v2.1.121 extended to non-interactive SDK/-p sessions).
• CLAUDE_CODE_FORWARD_SUBAGENT_TEXT: Includes subagent text and thinking in stream-json output, paired with a new --forward-subagent-text flag.
• CLAUDE_CODE_MAX_SUBAGENT_SPAWN_DEPTH: Nesting-depth cap on delegation, default 1 — subagents no longer spawn their own subagents, and the team roster stays flat.
• CLAUDE_CODE_SUBAGENT_MODELU: The trailing-U variant flagged as a likely typo in v2.1.84 has been removed.
• CLAUDE_CODE_SUBAGENT_PROMPT_CACHE_TTL
• CLAUDE_SUBAGENT_BG_SHELL_MAX_MS: Time cap for shell commands run by background subagents.

Frequently asked questions

All variables, searchable: Claude Code environment variables.