{"name":"CLAUDE_AGENT_SDK_CLIENT_APP","slug":"claude-agent-sdk-client-app","family":"env","title":"Environment variables","noun":"environment variable","description":"Names the application built on the Agent SDK. When set, it is sent on Anthropic API requests as the `x-client-app` header and appended as `client-app\/<value>` to Claude Code's `User-Agent` strings (`claude-cli\/...` and `claude-code\/...`). If the value is rejected as a header value, the error names this variable as its source.","description_source":"code","described_by":{"bundle":"2.1.286","author":"claude-opus-5-5"},"presence":{"first_seen":"2.1.138","removed_in":null,"in_current_build":true,"newest_mined":"2.1.308","builds":149,"mined_builds":149,"first_cited":{"version":"2.1.39","released_at":"2026-02-10 21:12:16","spans":1}},"aliases":[],"entries":[{"version":"2.1.39","anchor":"sdk-client-app-identification","heading":"SDK Client App Identification","line":null,"released_at":"2026-02-10 21:12:16","reason":"found in this entry's text"}],"entries_total":1,"docs":[{"source":"claude-code","path":"agent-sdk\/python","title":"Agent SDK reference - Python","documented":false},{"source":"claude-code","path":"agent-sdk\/typescript","title":"Agent SDK reference - TypeScript","documented":false},{"source":"claude-code","path":"errors","title":"Error reference","documented":false}],"docs_total":3,"gates":[],"related":[{"name":"CLAUDE_AGENT_SDK_DISABLE_BUILTIN_AGENTS","slug":"claude-agent-sdk-disable-builtin-agents","description":"Set to `1` to disable all built-in [subagent](\/docs\/en\/sub-agents) types such as Explore and Plan. Only applies in non-interactive mode (the `-p` flag). Useful for SDK users who want a blank slate. This also removes `general-purpose`, the subagent Claude Code runs when an Agent tool call omits `subagent_type`. Such a call then fails with [`subagent_type is required`](\/docs\/en\/errors#subagent-type-is-required)"},{"name":"CLAUDE_AGENT_SDK_DISABLE_MCP_MANIFESTS","slug":"claude-agent-sdk-disable-mcp-manifests","description":"The Agent SDK can now read tool lists from in-process MCP servers itself and pass them to the CLI when it starts"},{"name":"CLAUDE_AGENT_SDK_MCP_NO_PREFIX","slug":"claude-agent-sdk-mcp-no-prefix","description":"Set to `1` to skip the `mcp__<server>__` prefix on tool names from SDK-created MCP servers. Tools use their original names. SDK usage only"},{"name":"CLAUDE_AGENT_SDK_VERSION","slug":"claude-agent-sdk-version","description":"Your entrypoint and SDK version are checked against known values before being reported."}],"url":"https:\/\/changelogs.core-directive.com\/reference\/env\/claude-agent-sdk-client-app","family_url":"https:\/\/changelogs.core-directive.com\/reference\/env.json"}