Environment variables reference

This page centralizes environment variables visible in the analyzed runtime and already documented across model, session, tool, MCP, diagnostics, telemetry, and feature-gate pages.

Scope and caveats

• This is a source-visible environment-variable reference, not a guarantee that every variable is public, stable, or relevant to every launch mode.
• Some variables are hard gates; others are provider selectors, credentials, trace context, or runtime integration handoffs.
• Secret-bearing variables are listed for documentation only. Do not print or log their values in diagnostics.

Source anchors

Semantic alias	Source	Approximate location	String or symbol	Meaning
SdkCredentialEnv	cli.js	line ~43, byte 0x264c0	ANTHROPIC_API_KEY, ANTHROPIC_AUTH_TOKEN	Embedded SDK credential initialization path.
BedrockProviderEnv	cli.js	line ~253, byte 0x1ed452	CLAUDE_CODE_USE_BEDROCK	Provider classifier branch.
VertexProviderEnv	cli.js	line ~253, byte 0x1ed523	CLAUDE_CODE_USE_VERTEX	Vertex provider branch.
MainModelEnv	cli.js	line ~253, byte 0x20ed29	ANTHROPIC_MODEL	Model selection environment variable.
SmallFastModelEnv	cli.js	line ~253, byte 0x20eb73	ANTHROPIC_SMALL_FAST_MODEL	Small/fast model override.
DebugLogsDirEnv	cli.js	line ~62, byte 0x311ea	CLAUDE_CODE_DEBUG_LOGS_DIR	Debug-log directory override.
DebugLogLevelEnv	cli.js	line ~62, byte 0x31362	CLAUDE_CODE_DEBUG_LOG_LEVEL	Debug-log level override.
EssentialTrafficEnv	cli.js	line ~133, byte 0xea146	CLAUDE_CODE_DISABLE_NONESSENTIAL_TRAFFIC	Essential-traffic-only gate.
DisableTelemetryEnv	cli.js	line ~133, byte 0xea198	DISABLE_TELEMETRY	Telemetry disable gate.
DoNotTrackEnv	cli.js	line ~133, byte 0xea1d1	DO_NOT_TRACK	Telemetry disable gate.
DisableErrorReportingEnv	cli.js	line ~133, byte 0xea692	DISABLE_ERROR_REPORTING	Error-reporting disable gate.
DisableGrowthBookEnv	cli.js	line ~432, byte 0x2fe03e	DISABLE_GROWTHBOOK	Feature-evaluation kill switch.
McpToolTimeoutEnv	cli.js	line ~4980, byte 0x937240	MCP_TIMEOUT	MCP tool timeout environment variable.
McpConnectTimeoutEnv	cli.js	line ~4980, byte 0x9372a0	MCP_CONNECT_TIMEOUT_MS	MCP connection timeout environment variable.
SessionAccessTokenEnv	cli.js	line ~2624, byte 0x6519e7	CLAUDE_CODE_SESSION_ACCESS_TOKEN	Remote/session ingress token source.
WebSocketAuthFdEnv	cli.js	line ~2624, byte 0x6516a5	CLAUDE_CODE_WEBSOCKET_AUTH_FILE_DESCRIPTOR	WebSocket auth file-descriptor handoff.
OtelHeadersEnv	cli.js	line ~2630, byte 0x654a73	OTEL_EXPORTER_OTLP_HEADERS	OpenTelemetry exporter env surface.
TraceparentEnv	cli.js	line ~2027, byte 0x526c31	TRACEPARENT	Trace-context propagation.
DisableCronEnv	cli.js	line ~1091, byte 0x4806fd	CLAUDE_CODE_DISABLE_CRON	Cron/scheduled-task kill switch.

Authentication and credential handoff

Variable	Purpose	Owner
ANTHROPIC_API_KEY	API-key credential source.	Models, providers, and auth
ANTHROPIC_AUTH_TOKEN	Bearer/OAuth-style credential source.	Models, providers, and auth
CLAUDE_CODE_OAUTH_TOKEN	OAuth token input surface.	Models, providers, and auth
CLAUDE_CODE_OAUTH_TOKEN_FILE_DESCRIPTOR	OAuth token via file descriptor.	Models, providers, and auth
CLAUDE_CODE_API_KEY_FILE_DESCRIPTOR	API key via file descriptor.	Models, providers, and auth
CLAUDE_CODE_SESSION_ACCESS_TOKEN	Remote/session ingress token.	Remote control and teleport
CLAUDE_CODE_WEBSOCKET_AUTH_FILE_DESCRIPTOR	WebSocket auth handoff for bridge/session transports.	Session API, events, and storage

Provider and model selection

Variable	Effect	Owner
CLAUDE_CODE_USE_BEDROCK	Selects Bedrock provider branch.	Models, providers, and auth
CLAUDE_CODE_USE_VERTEX	Selects Vertex provider branch.	Models, providers, and auth
CLAUDE_CODE_USE_FOUNDRY	Selects Foundry provider branch.	Models, providers, and auth
CLAUDE_CODE_USE_ANTHROPIC_AWS	Selects Anthropic AWS provider branch.	Models, providers, and auth
CLAUDE_CODE_USE_MANTLE	Selects Mantle provider branch.	Models, providers, and auth
ANTHROPIC_MODEL	Environment-level main model override.	Model selection, calls, usage, quota, and billing
ANTHROPIC_SMALL_FAST_MODEL	Small/fast helper model override.	Model selection, calls, usage, quota, and billing
AWS_REGION, AWS_DEFAULT_REGION	AWS-region selection surfaces for AWS-like provider paths.	Models, providers, and auth
CLOUD_ML_REGION	Google/Vertex region surface.	Models, providers, and auth
ANTHROPIC_BASE_URL	Custom API/base URL surface.	Models, providers, and auth

Diagnostics, telemetry, and tracing

Variable	Effect	Owner
DEBUG, DEBUG_SDK	Enables debug behavior in selected paths.	Diagnostics and debug logs
CLAUDE_CODE_DEBUG_LOGS_DIR	Overrides debug log directory.	Diagnostics and debug logs
CLAUDE_CODE_DEBUG_LOG_LEVEL	Sets debug log level threshold when recognized.	Diagnostics and debug logs
CLAUDE_CODE_DISABLE_NONESSENTIAL_TRAFFIC	Switches to essential-traffic mode.	Telemetry and tracing
DISABLE_TELEMETRY	Disables telemetry.	Telemetry and tracing
DO_NOT_TRACK	Disables telemetry.	Telemetry and tracing
DISABLE_ERROR_REPORTING	Disables error reporting.	Telemetry and tracing
DISABLE_GROWTHBOOK	Disables GrowthBook feature evaluation.	Feature gates reference
TRACEPARENT, TRACESTATE	W3C trace-context propagation.	Telemetry and tracing
BETA_TRACING_ENDPOINT	Beta trace/log exporter endpoint base.	Telemetry and tracing
OTEL_*	OpenTelemetry metrics/logs/traces exporter configuration.	Telemetry and tracing
OTEL_LOG_TOOL_DETAILS, OTEL_LOG_TOOL_CONTENT, OTEL_LOG_USER_PROMPTS	Controls how much tool/user detail may be logged.	Telemetry and tracing

MCP, plugins, and agents

Variable	Effect	Owner
MCP_TIMEOUT	MCP tool-call timeout, with a documented default fallback.	MCP, plugins, and hooks
MCP_CONNECT_TIMEOUT_MS	MCP connection timeout.	MCP, plugins, and hooks
MCP_CONNECTION_NONBLOCKING	Runtime MCP connection non-blocking gate.	MCP, plugins, and hooks
CLAUDE_CODE_PLUGIN_PREFER_HTTPS	Plugin transport preference gate.	Feature gates reference
CLAUDE_CODE_PLUGIN_USE_ZIP_CACHE	Plugin zip-cache gate.	Feature gates reference
CLAUDE_CODE_SYNC_PLUGIN_INSTALL	Synchronous plugin installation behavior.	Feature gates reference
CLAUDE_AGENT_SDK_DISABLE_BUILTIN_AGENTS	Built-in agent availability gate.	Feature gates reference
CLAUDE_CODE_DISABLE_AGENT_VIEW	Agent UI/view gate.	Feature gates reference

Feature, context, UI, and update gates

Variable	Effect	Owner
CLAUDE_CODE_DISABLE_CRON	Disables scheduled tasks / Kairos cron paths.	Agent runtime, scheduling, and completion
CLAUDE_CODE_DISABLE_ADVISOR_TOOL	Advisor/permission-adjacent tool gate.	Feature gates reference
CLAUDE_CODE_ENABLE_EXPERIMENTAL_ADVISOR_TOOL	Experimental advisor tool gate.	Feature gates reference
CLAUDE_CODE_DISABLE_1M_CONTEXT	Context-window feature gate.	Feature gates reference
DISABLE_COMPACT	Context compaction gate.	Feature gates reference
DISABLE_INTERLEAVED_THINKING	Interleaved-thinking gate.	Feature gates reference
USE_API_CONTEXT_MANAGEMENT	API-side context-management gate.	Feature gates reference
CLAUDE_CODE_DISABLE_ALTERNATE_SCREEN, CLAUDE_CODE_NO_FLICKER, CLAUDE_CODE_DISABLE_MOUSE, CLAUDE_CODE_FORCE_SYNC_OUTPUT, CLAUDE_CODE_ACCESSIBILITY, CLAUDE_CODE_DISABLE_TERMINAL_TITLE	Terminal rendering/accessibility gates.	Feature gates reference
DISABLE_UPDATES, DISABLE_AUTOUPDATER, FORCE_AUTOUPDATE_PLUGINS	Native/plugin updater behavior gates.	Updater and doctor

Interpretation rules

1. Treat credential and token variables as sensitive; never capture values in examples or logs.
2. Prefer this page for variable names, and the owner pages for call paths and semantics.
3. Treat CLAUDE_CODE_USE_* provider variables as provider selectors; do not assume multiple provider selectors compose safely.
4. Treat tengu_* strings as feature/telemetry signals, not user-settable environment variables unless an explicit env var is visible.

Related docs

• Diagnostics and debug logs
• Telemetry and tracing
• Feature gates reference
• Updater and doctor
• Models, providers, and auth
• MCP, plugins, and hooks
• Remote control and teleport