{"name":"BROWSER","slug":"browser","family":"env","title":"Environment variables","noun":"environment variable","description":"The command Claude Code runs to open a URL in a browser, falling back to `xdg-open` on Linux; a value other than `true` also stops an SSH session or a Linux session with no display from being treated as headless, so MCP authorization and sign-in flows treat the session as able to open a browser. Claude Code sets it too: background sessions it launches get `BROWSER=true` (a no-op command) except in exec mode, and while a terminal is attached they take that terminal's value. It is also on Claude Code's lists of program-launching variables, which some hardened subprocess environments drop.","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":null},"aliases":[],"entries":[{"version":"2.1.191","anchor":"headless-environment-detection-improvement","heading":"Headless Environment Detection Improvement","line":null,"released_at":"2026-06-24 18:54:40","reason":"found in this entry's text"}],"entries_total":1,"docs":[{"source":"api","path":"about-claude\/api-credits-for-subscribers","title":"api-credits-for-subscribers","documented":false},{"source":"api","path":"about-claude\/models\/migration-guide","title":"Or, for the model with the same capabilities and no access approval requirement:","documented":false},{"source":"api","path":"about-claude\/pricing","title":"pricing","documented":false},{"source":"api","path":"agents-and-tools\/mcp-tunnels\/troubleshooting","title":"troubleshooting","documented":false},{"source":"api","path":"agents-and-tools\/tool-use\/browser-use-sdk","title":"browser-use-sdk","documented":false},{"source":"api","path":"agents-and-tools\/tool-use\/browser-use-tool","title":"browser-use-tool","documented":false},{"source":"api","path":"agents-and-tools\/tool-use\/computer-use-tool","title":"computer-use-tool","documented":false},{"source":"api","path":"agents-and-tools\/tool-use\/define-tools","title":"define-tools","documented":false},{"source":"api","path":"agents-and-tools\/tool-use\/fine-grained-tool-streaming","title":"fine-grained-tool-streaming","documented":false},{"source":"api","path":"agents-and-tools\/tool-use\/handle-tool-calls","title":"handle-tool-calls","documented":false}],"docs_total":12,"gates":[],"related":[],"url":"https:\/\/changelogs.core-directive.com\/reference\/env\/browser","family_url":"https:\/\/changelogs.core-directive.com\/reference\/env.json"}