{"version":"2.1.219","anchor":"opus-5-gets-an-extra-system-prompt-instruction-restricting-a","canonical_anchor":"opus-5-gets-an-extra-system-prompt-instruction-restricting-a","heading":"Opus 5 gets an extra system-prompt instruction restricting AgentTool, workflows and deep-research","tier":"notice","area":"System Prompt","scope":null,"heads_up":null,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.219\/e\/opus-5-gets-an-extra-system-prompt-instruction-restricting-a","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.219","markdown":"### Opus 5 gets an extra system-prompt instruction restricting AgentTool, workflows and deep-research\n\nOn Opus 5, Claude is told not to spawn subagents, workflows or deep research unless you ask.\n\n**What**\n\nModels carrying the opus-5 prompt bundle now receive a built-in instruction telling Claude not to spawn subagents or run workflows and deep-research unless the user asked for it.\n\n**Details**\n\n- the `tengu_heron_brook` injection previously came only from client data or the remote flag string; it now falls back to a built-in two-line block\n- the fallback applies when the model carries the opus_5_prompt_bundle capability\n- killswitch is `tengu_fennel_godwit`\n- the applied event still fires as `tengu_heron_brook_applied` with `fromClientData: !1` on this path\n\n**Evidence**\n\n`Do not use workflows or deep-research unless the user requested it`\n\n- Flag `tengu_heron_brook`: Not enough to say (read for one account on one subscription tier against v2.1.219; this account: no value returned, anonymous baseline: no value returned, compiled default: not a boolean we can read) These values were read against a different version of Claude Code, so treat them as the nearest reading available instead of one taken on this release.\n- Flag `tengu_fennel_godwit`: Off in both readings (read for one account on one subscription tier against v2.1.219; this account: off, anonymous baseline: off, compiled default: not a boolean we can read) These values were read against a different version of Claude Code, so treat them as the nearest reading available instead of one taken on this release.\n- Area: System Prompt\n- Tier: You'll notice\n- Useful: 4\/5\n- Signal: 0\/5"}