{"name":"CLAUDE_AGENT_SDK_MCP_NO_PREFIX","slug":"claude-agent-sdk-mcp-no-prefix","family":"env","title":"Environment variables","noun":"environment variable","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","description_source":"docs","described_by":{"doc":"claude-code\/env-vars","title":"Environment variables"},"presence":{"first_seen":"2.1.138","removed_in":null,"in_current_build":true,"newest_mined":"2.1.309","builds":150,"mined_builds":150,"first_cited":null},"aliases":[],"entries":[{"version":"2.1.295","anchor":"auto-mode-resolves-toolaliases-for-mcp-tools-behind-tengu-so","heading":"Auto mode can pick up aliased MCP tools so the safety check covers them","line":"Behind a switch that is off by default, auto mode registers tools reached through `toolAliases` or warns when an allow rule would skip its check","released_at":"2026-10-08 18:22:58","reason":"found in this entry's text"},{"version":"2.1.248","anchor":"mcp-environment-variables-parsed-once-with-bounds","heading":"MCP environment variables parsed once, with bounds","line":"MCP_TOOL_TIMEOUT is parsed with a minimum of 1 and ENABLE_MCP_LARGE_OUTPUT_FILES only disables when explicitly false.","released_at":"2026-08-27 20:35:36","reason":"found in this entry's text"}],"entries_total":2,"docs":[{"source":"claude-code","path":"env-vars","title":"Environment variables","documented":true}],"docs_total":1,"gates":[],"related":[{"name":"CLAUDE_AGENT_SDK_CLIENT_APP","slug":"claude-agent-sdk-client-app","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."},{"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_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-mcp-no-prefix","family_url":"https:\/\/changelogs.core-directive.com\/reference\/env.json"}