SDK and Automation

These variables help a program that runs Claude Code as a child process. They say which surface started it, how session events reach the host, and which binary the Agent SDK looks for. Most people never set them. Hosts such as the Agent SDK set them for you.

This page lists 22 variables. These are for a host program that starts Claude Code. Set them in the child process environment. Project env cannot set most of them before trust.

Example

CLAUDE_CODE_ENTRYPOINT=sdk-cli claude -p "List the files" --output-format stream-json

CLAUDE_CODE_ENTRYPOINT tells Claude Code which host started it. The host sets it before the process starts.

Variables

The table is sorted by name. See Environment Variables for what each column and badge means.

Variable	Status	What it does	Values and default	Notes
ANTHROPIC_ENVIRONMENT_ID	Undocumented	The bundled Anthropic SDK EnvironmentWorker reads it as the default environment ID when a work item call passes none.	Text. The call fails with an error if no ID comes from any source	Bundled SDK work polling. Not set from project env before trust
ANTHROPIC_ENVIRONMENT_KEY	Undocumented	The bundled Anthropic SDK EnvironmentWorker reads it as the fallback environment key. A work item needs it when its secret has no sessions_token.	Text	Bundled SDK work polling. Not set from project env before trust
ANTHROPIC_SESSION_ID	Undocumented	The bundled Anthropic SDK EnvironmentWorker reads it as the default session ID for a work item.	Text. The call fails with an error if no ID comes from any source	Bundled SDK work polling. Not set from project env before trust
ANTHROPIC_WEBHOOK_SIGNING_KEY	Undocumented	The bundled SDK client reads it as the default webhook signing key. It is null when unset.	Text. SDK constructor default	Bundled SDK client. Not set from project env before trust
ANTHROPIC_WORK_ID	Undocumented	The bundled Anthropic SDK EnvironmentWorker reads it as the default work item ID.	Text. The call fails with an error if no ID comes from any source	Bundled SDK work polling. Not set from project env before trust
ANTHROPIC_WORK_SECRET	Undocumented	The bundled Anthropic SDK EnvironmentWorker reads it as the default work secret.	Text	Bundled SDK work polling. Not set from project env before trust
CLAUDE_CODE_CONFIG_PROBE	Undocumented	In the IDE config probe, skips the awsAuthRefresh and gcpAuthRefresh commands and the credential helper prefetch.	On or off, off by default. Also in a list of host-controlled names	IDE config probe, Bedrock and Vertex auth refresh
CLAUDE_CODE_EDITOR_CODELIVERY	Undocumented	Lets a relayed human message carry an artifact_followup ack with an https URL of at most 2048 chars.	On or off, off by default	Relay and remote sessions only
CLAUDE_CODE_EMIT_SESSION_STATE_EVENTS	Documented	Adds session_state_changed system messages to the output stream.	On or off, off by default. Code emits a normal event when set, else a host-only event when CLAUDE_CODE_SDK_READS_SESSION_STATE is set	SDK and --print stream-json
CLAUDE_CODE_ENTRYPOINT	Undocumented	Names the surface that started Claude Code, such as cli, sdk-ts, claude-vscode, or remote. Many code paths branch on it.	Text. Set by Claude Code at startup when empty (mcp for mcp serve, sdk-cli for SDK CLI) and set to sdk-ts by the TS SDK	All sessions
CLAUDE_CODE_GENTLE_PARASOL	Undocumented Gated	Overrides a feature flag experiment, which applies a secondary reminder to model requests.	Text. Logs secondary_reminder when applied	API requests
CLAUDE_CODE_HUMBLE_HAMMOCK	Undocumented Gated	Forces the echoWireToolInputs behavior on or off ahead of the flag. Probe: Adds wire_tool_inputs (raw tool_use.input) to the assistant event when a tool runs. See Probes.	On, off, or unset. Unset falls back to echoWireToolInputs and then to a feature flag	All sessions
CLAUDE_CODE_JIT_POLICY_AFTER_STARTUP	Undocumented	Sets the Bun JIT policy 10 seconds after start. Without it the policy is set to 1.	On or off. Whole number 1 to 100, digits only. A truthy value loads a module that applies the value	All sessions, Bun build
CLAUDE_CODE_LARCH_CISTERN	Undocumented Gated	Overrides the larch_cistern experiment value for the model. Probe: Adds a "Corrections" section to the system prompt (avoid excessive self-correction). See Probes.	On or off. Passed to the same per-model helper as CLAUDE_CODE_AMBER_ASTROLABE. A false value counts as unset	All sessions
CLAUDE_CODE_POLL_EVENTS	Undocumented	Lets a host send poll events to the session as <event> envelopes. The code rejects them when the host did not set it.	On or off. Poll events also need permission mode auto	SDK and host sessions
CLAUDE_CODE_REMOVE_PROMPT_STRINGS	Undocumented	Removes listed strings from prompts for prompt ablation tests. It overrides the remove_prompt_strings client data.	JSON text. A bad value logs a warning. Telemetry event a feature flag	All sessions
CLAUDE_CODE_SDK_READS_STARTUP_MARKS	Undocumented	Tells Claude Code that the SDK host reads startup marks. The Agent SDK sets it for startup() and prewarm(). The CLI then writes lines with a startup_mark field.	On or off	SDK and print mode
CLAUDE_CODE_SDK_READS_SESSION_STATE	Undocumented	Tells Claude Code that the SDK host reads session state. Claude Code then sends session_state_changed events marked sdk_host_only.	On or off. Set by Claude Code to 1 in the SDK child env unless the host already set it	SDK and print mode. Set by Claude Code
CLAUDE_CODE_SIMULATE_PROXY_USAGE	Undocumented	Simulates proxy use in request shaping. Claude Code then skips steps such as the thinking display update. A Probes run saw no anthropic-beta header.	On or off	API requests
CLAUDE_CODE_SUPERVISED	Undocumented	Tells Claude Code that a supervisor restarts it. On an uncaught exception it then exits at once instead of staying alive.	On or off	Supervised or managed runs
CLAUDE_CODE_TETHER_LIVE	Undocumented Gated	Forces the tether-live gate on or off. It replaces the feature flag and also gates the kept-reminder delivery.	On or off. Needs the first-party provider. Without it, the flag decides, and only for some builds or users	First-party provider only
SDK_NATIVE_BIN	Undocumented	Sets the native binary file name that the Agent SDK looks for.	Text, claude by default. Joined to the platform package path @anthropic-ai/claude-agent-sdk-<os>-<arch>	Agent SDK launch. Not set from project env before trust

How It Works

A host starts claude with its own environment. Claude Code sets CLAUDE_CODE_ENTRYPOINT itself when it is empty (mcp for mcp serve, sdk-cli for the SDK command line). Other variables here switch on extra stream events or tell Claude Code that a supervisor restarts it.

Related Pages

• Environment Variables: how Claude Code reads variables and which value wins.
• Headless and Print Mode
• Remote and Cloud Sessions
• Undocumented Items: every item that only the program shows.

Source: the program (variable names found in the 2.1.304 binary) and the Environment Variables page of the official docs.