The Complete List of Claude Code Environment Variables (500+)#

Published on March 17, 2026

Part of the Claude Code Version Tracker series. | Official Env Vars

Claude Code has over 500 environment variables scattered across its binary. Most are undocumented. This is the definitive reference — cross-compiled from our binary extraction series, community research, and the comprehensive gist by unkn0wncode.

Jump to what you need:

• API & Authentication — API keys, tokens, custom endpoints
• Model Configuration — model overrides, output tokens, thinking
• AWS Bedrock — Bedrock setup, streaming fix for 400 errors
• Google Vertex AI
• Azure Foundry
• OAuth & Login
• Core Configuration — shell, config dir, entrypoint
• Feature Flags (Enable) — opt-in features
• Feature Flags (Disable) — opt-out features
• Bash & Shell
• Tool Configuration — concurrency, glob, timeouts
• MCP (Model Context Protocol)
• Plugin System
• Context & Compaction — auto-compaction, context window
• Agent Teams & Cowork
• Remote / Server Mode
• IDE Integration
• OpenTelemetry (OTEL)
• Proxy & TLS — enterprise proxy, mTLS
• Debug & Profiling
• Command Disablers
• Agent SDK
• Tmux Integration
• Internal & Sandbox

Not listed here: CI/CD detection vars (GitHub Actions, GitLab CI, etc.), terminal emulator detection, cloud platform detection, system/runtime vars, Node.js/Bun internals, gRPC config, and Azure Identity vars. These are read-only environment detection — you wouldn't set them yourself. See the full gist for the complete unfiltered list.

API & Authentication#

Tip: If you run Claude Code through a proxy like claude-code-router, set ANTHROPIC_BASE_URL and consider CLAUDE_CODE_ATTRIBUTION_HEADER=0 to prevent the billing header from breaking prompt caching. For a deep dive on this issue — including Bedrock 400 errors and step-by-step fixes — see our CLAUDE_CODE_ATTRIBUTION_HEADER guide.

Model Configuration#

Tip: CLAUDE_CODE_SUBAGENT_MODEL is useful for cost control — set subagents to use Haiku while keeping the main conversation on Opus/Sonnet.

AWS Bedrock#

Fix: Bedrock "eager_input_streaming" 400 Error#

If you use Claude Code with AWS Bedrock and see this error:

API Error: 400 tools.0.custom.eager_input_streaming: Extra inputs are not permitted

This is caused by Claude Code adding eager_input_streaming: true to tool definitions in API requests. Bedrock's Converse API may reject this as an unrecognized parameter, depending on your Bedrock configuration and region.

CLAUDE_CODE_ENABLE_FINE_GRAINED_TOOL_STREAMING controls the tool streaming behavior. Try toggling it:

# Option 1: Explicitly enable fine-grained streaming (uses compatible code path)
CLAUDE_CODE_ENABLE_FINE_GRAINED_TOOL_STREAMING=1 CLAUDE_CODE_USE_BEDROCK=1 claude

# Option 2: Disable it if your Bedrock config rejects the parameter
CLAUDE_CODE_ENABLE_FINE_GRAINED_TOOL_STREAMING=0 CLAUDE_CODE_USE_BEDROCK=1 claude

# Or add to your shell profile
export CLAUDE_CODE_ENABLE_FINE_GRAINED_TOOL_STREAMING=1

Background: This issue first surfaced in Claude Code v2.1.72 (#32765), which started sending eager_input_streaming to Bedrock before the API fully supported it. The feature request originated from #26941, where users reported 10–20 second permission prompt latency on Bedrock — fine-grained streaming reduces this to 1–3 seconds. Anthropic has since made fine-grained tool streaming GA across all platforms including Bedrock, but some configurations may still need this env var toggled.

If toggling this var doesn't help, also check that you're on the latest Claude Code version (v2.1.73+ includes the fix).

Google Vertex AI#

Azure Foundry#

OAuth & Login#

Core Configuration#

Tip: CLAUDE_CODE_EXTRA_BODY is powerful for advanced users — it merges arbitrary JSON into every API request body. Useful for passing provider-specific parameters.

Feature Flags (Enable)#

Feature Flags (Disable)#

Tip: CLAUDE_CODE_DISABLE_AUTO_MEMORY=1 is useful in CI/CD or when running automated pipelines where you don't want memory files created. CLAUDE_CODE_DISABLE_CLAUDE_MDS=1 is useful for testing without project instructions.

Bash & Shell#

Tool Configuration#

MCP (Model Context Protocol)#

Tip: If you have many MCP servers configured and startup is slow, increase MCP_SERVER_CONNECTION_BATCH_SIZE to connect to more servers in parallel.

Plugin System#

Context & Compaction#

Tip: CLAUDE_AUTOCOMPACT_PCT_OVERRIDE is particularly useful. The default auto-compaction triggers at ~83% context usage (values above this are silently capped). If you want earlier compaction (preserving more space for responses), try CLAUDE_AUTOCOMPACT_PCT_OVERRIDE=75. See the complete CLAUDE_AUTOCOMPACT_PCT_OVERRIDE guide for recommended values by use case, the cap bug details, and related compaction variables.

Agent Teams & Cowork#

Remote / Server Mode#

IDE Integration#

OpenTelemetry (OTEL)#

Tip: OTEL support makes Claude Code observable in enterprise environments. Point OTEL_EXPORTER_OTLP_ENDPOINT at your Grafana/Datadog/Honeycomb and get full traces of every tool call, API request, and thinking step.

Proxy & TLS#

Tip: Enterprise users behind corporate proxies: set CLAUDE_CODE_CLIENT_CERT and CLAUDE_CODE_CLIENT_KEY for mutual TLS. If your proxy intercepts TLS, point NODE_EXTRA_CA_CERTS at your corporate CA bundle.

Debug & Profiling#

Tip: Start debugging with CLAUDE_DEBUG=1 claude. If you need deeper diagnostics, add CLAUDE_CODE_PROFILE_STARTUP=1 and check the output for slow initialization steps. See our debugging guide for common issues.

Command Disablers#

These disable specific Claude Code CLI commands:

Agent SDK#

Tmux Integration#

Internal & Sandbox#

These are used internally by Claude Code for demo environments, testing, and specialized deployments:

Quick Start Recipes#

# Debug mode
CLAUDE_DEBUG=1 claude

# Custom API proxy
ANTHROPIC_BASE_URL=https://my-proxy.com/v1 CLAUDE_CODE_ATTRIBUTION_HEADER=0 claude

# Bedrock with streaming fix
CLAUDE_CODE_USE_BEDROCK=1 CLAUDE_CODE_ENABLE_FINE_GRAINED_TOOL_STREAMING=1 claude

# Cost-effective subagents
CLAUDE_CODE_SUBAGENT_MODEL=claude-haiku-4-5-20251001 claude

# Earlier context compaction (at 80%)
CLAUDE_AUTOCOMPACT_PCT_OVERRIDE=80 claude

# CI/CD mode — minimal noise
CLAUDE_CODE_DISABLE_AUTO_MEMORY=1 CLAUDE_CODE_DISABLE_FEEDBACK_SURVEY=1 DISABLE_AUTOUPDATER=1 claude -p "run tests"

# Enterprise with mTLS proxy
HTTPS_PROXY=https://proxy.corp.com:8443 CLAUDE_CODE_CLIENT_CERT=/path/to/cert.pem CLAUDE_CODE_CLIENT_KEY=/path/to/key.pem claude

# Agent Teams
CLAUDE_CODE_EXPERIMENTAL_AGENT_TEAMS=1 claude

Sources#

This reference was compiled from:

• Our binary extraction series: v2.1.19 → v2.1.69 → v2.1.70 → v2.1.72 → v2.1.73 → v2.1.74
• unkn0wncode's comprehensive gist (500+ variables from source analysis)
• Community reports from GitHub issues and forums

For version-by-version changelogs, see the Claude Code Version Tracker.

This analysis is conducted for independent security research and interoperability purposes under fair use principles. All trademarks belong to their respective owners. The information presented here documents publicly observable behavior of installed software and is not intended to circumvent any technological protection measures, infringe on intellectual property rights, or encourage unauthorized use. Use these findings at your own discretion.

Related: Context Window Management Guide | Claude Code Productivity Tips | Debugging Claude Code Issues