{"name":"tengu_heron_tallow","slug":"tengu-heron-tallow","family":"flag","title":"Feature flags","noun":"feature flag","description":"Default `false`. Changes the hint added when the model calls a tool that is not available: for a known tool it reads `<tool> is disabled for this session, in subagents as well as here.` instead of `exists but is not enabled in this context`, and for Glob or Grep when Bash is also unavailable it reads `<tool> is disabled for this session.` `CLAUDE_CODE_HERON_TALLOW` turns on the same wording.","description_source":"code","described_by":{"bundle":"2.1.228","author":"claude-opus-5-5"},"presence":{"first_seen":"2.1.217","removed_in":"2.1.229","in_current_build":false,"newest_mined":"2.1.308","builds":11,"mined_builds":149,"first_cited":null},"aliases":[],"entries":[{"version":"2.1.217","anchor":"tengu-heron-tallow-new-feature-gate-feature-flagged","heading":"tengu_heron_tallow \u2014 New Feature Gate [Feature-Flagged]","line":null,"released_at":"2026-07-21 19:55:38","reason":"gate cited by this entry, found in this entry's text"}],"entries_total":1,"docs":[],"docs_total":0,"gates":[{"version":"2.1.217","state":"off","account":false,"baseline":false,"code_default":null}],"related":[{"name":"tengu_heron_brook","slug":"tengu-heron-brook","description":"On some models Claude will stop spinning up subagents or research workflows unless you actually ask for it."},{"name":"tengu_heron_brook_applied","slug":"tengu-heron-brook-applied","description":"On some models Claude will stop spinning up subagents or research workflows unless you actually ask for it."}],"url":"https:\/\/changelogs.core-directive.com\/reference\/flag\/tengu-heron-tallow","family_url":"https:\/\/changelogs.core-directive.com\/reference\/flag.json"}