CLAUDE_CODE_SIMPLE_SYSTEM_PROMPT

Updated October 13, 2026 by Alex Sorokoletov

CLAUDE_CODE_SIMPLE_SYSTEM_PROMPT is a Claude Code environment variable: Switches to a reduced system prompt, stripping out the non-essential guidance sections that bulk up the default prompt. Useful in latency-sensitive or token-budget-constrained deployments where the full prompt overhead isn't justified — SDK or CI contexts where Claude is given a narrow task and needs to start fast. Added between v2.1.114 and v2.1.117 and still present in v2.1.294. It is listed in the official reference.

Status	Present in v2.1.294
Added	Added between v2.1.114 and v2.1.117
Category	Other
Official docs	Listed

How to set it

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

export CLAUDE_CODE_SIMPLE_SYSTEM_PROMPT=<value>
claude

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

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

Release notes that mention it

Related variables

CLAUDE_CODE_SYSTEM_PROMPT_GB_FEATURE: Names a GrowthBook feature flag whose value overrides the system prompt — but only when CLAUDE_CODE_REMOTE is set.
CLAUDE_CODE_FLEETVIEW_SIMPLE: Forces the simplified FleetView layout, the multi-agent monitoring surface.
CLAUDE_CODE_MID_CONVERSATION_SYSTEM: Inject a system message mid-conversation.
CLAUDE_CODE_PROMPT_CACHE_TTL
CLAUDE_CODE_SIMPLE: Simplified mode; disables CLAUDE.md and attachments (renamed from CLAUDE_CODE_SIMPLETON).
CLAUDE_CODE_VERIFY_PROMPT: The verify flow was reworked; the standalone prompt override no longer maps to how verification runs.
CLAUDE_CODE_APPEND_PROMPT_HEAD
CLAUDE_CODE_HOST_PROMPT_SUPERSEDES_RECORD

Frequently asked questions

What does CLAUDE_CODE_SIMPLE_SYSTEM_PROMPT do?

Switches to a reduced system prompt, stripping out the non-essential guidance sections that bulk up the default prompt. Useful in latency-sensitive or token-budget-constrained deployments where the full prompt overhead isn't justified — SDK or CI contexts where Claude is given a narrow task and needs to start fast.

Which Claude Code version has CLAUDE_CODE_SIMPLE_SYSTEM_PROMPT?

Added between v2.1.114 and v2.1.117 and still present in v2.1.294.

How do I set CLAUDE_CODE_SIMPLE_SYSTEM_PROMPT?

Export it before starting Claude Code (export CLAUDE_CODE_SIMPLE_SYSTEM_PROMPT=value), or add it to the "env" object in ~/.claude/settings.json to apply it to every session.

All variables, searchable: Claude Code environment variables.