{"name":"DISABLE_PROMPT_CACHING_MYTHOS","slug":"disable-prompt-caching-mythos","family":"env","title":"Environment variables","noun":"environment variable","description":"When true, Claude Code's prompt-caching check returns false for any model whose ID contains `claude-mythos-`. That check decides whether a request uses prompt caching when the caller does not set `enablePromptCaching` itself, and also gates some other cache-dependent behaviour.","description_source":"code","described_by":{"bundle":"2.1.286","author":"claude-opus-5-5"},"presence":{"first_seen":"2.1.170","removed_in":null,"in_current_build":true,"newest_mined":"2.1.309","builds":121,"mined_builds":150,"first_cited":null},"aliases":[],"entries":[],"entries_total":0,"docs":[],"docs_total":0,"gates":[],"related":[{"name":"DISABLE_PROMPT_CACHING","slug":"disable-prompt-caching","description":"Parallel workflow agents stagger their first call to share cache; tune with an env var."},{"name":"DISABLE_PROMPT_CACHING_FABLE","slug":"disable-prompt-caching-fable","description":"When true, Claude Code's prompt-caching check returns false for any model whose ID contains `claude-fable-` or that matches `ANTHROPIC_DEFAULT_FABLE_MODEL`. That check decides whether a request uses prompt caching when the caller does not set `enablePromptCaching` itself, and also gates some other cache-dependent behaviour."},{"name":"DISABLE_PROMPT_CACHING_HAIKU","slug":"disable-prompt-caching-haiku","description":"`DISABLE_PROMPT_CACHING_HAIKU` now also turns off caching for any request whose model resolves to the configured Haiku model"},{"name":"DISABLE_PROMPT_CACHING_OPUS","slug":"disable-prompt-caching-opus","description":"When true, Claude Code's prompt-caching check returns false for the resolved Opus model (`ANTHROPIC_DEFAULT_OPUS_MODEL` when set, otherwise the default Opus model). That check decides whether a request uses prompt caching when the caller does not set `enablePromptCaching` itself, and also gates some other cache-dependent behaviour."},{"name":"DISABLE_PROMPT_CACHING_SONNET","slug":"disable-prompt-caching-sonnet","description":"When true (`1`, `true`, `yes` or `on`), prompt caching is off by default for requests whose model equals the default Sonnet model (`ANTHROPIC_DEFAULT_SONNET_MODEL` when set, otherwise the built-in Sonnet default). While it is set, a startup warning reads `Prompt caching off (...), requests will be slower and cost more`."}],"url":"https:\/\/changelogs.core-directive.com\/reference\/env\/disable-prompt-caching-mythos","family_url":"https:\/\/changelogs.core-directive.com\/reference\/env.json"}