CLAUDE_CODE_DISABLE_FILE_MENTIONS

Updated October 23, 2026 by Alex Sorokoletov

CLAUDE_CODE_DISABLE_FILE_MENTIONS is a Claude Code environment variable: Switches @ file mentions from inlining file contents to passing their paths, which Claude reads with its file tools on demand. Keeps large mentioned files out of the prompt until they are needed. New in v2.1.299. Added in v2.1.299 and still present in v2.1.310. 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_DISABLE_FILE_MENTIONS=<value>
claude

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

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

Release notes that mention it

• Claude Code Version Tracker: Undocumented Env Vars, Feature Gates & Models
• claude-code-env-vars-v2-1-299

Related variables

• CLAUDE_CODE_DISABLE_FILE_CHECKPOINTING: Git-based file checkpointing/backup.
• CLAUDE_CODE_DISABLE_ARTIFACT
• CLAUDE_CODE_DISABLE_ATTACHMENTS: File/image attachments.
• CLAUDE_CODE_DISABLE_CFC_PROMPT
• CLAUDE_CODE_DISABLE_COMMAND_INJECTION_CHECK: Previously allowed disabling command injection detection.
• CLAUDE_CODE_DISABLE_CRON: Disable cron/scheduled task functionality.
• CLAUDE_CODE_DISABLE_EXPERIMENTAL_BETAS: Experimental beta API features.
• CLAUDE_CODE_DISABLE_EXPLORE_INHERIT_CAP: Lets the built-in Explore search agent run at the parent model instead of a cheaper capped default.

Frequently asked questions

All variables, searchable: Claude Code environment variables.