What probably matters to youSection of the release
What
A new "max effort" mode was added: a helper decides when to force maximum effort, gated by a reminder-enabled check before it's applied.
A status-line reminder ("Max effort · … · /effort to change") is shown when effort is set to max; whether it appears is controlled by the CLAUDE_CODE_MAX_EFFORT_REMINDER environment variable, falling back to a remote flag (tengu_proud_clover, off by default unless enabled server-side).
The VS Code extension's feature-gate table gained the corresponding max-effort reminder gate, wired from maxEffortReminderEnabled.
The reminder is shown in a warning color rather than a subtle one when the environment variable or flag is set.
Underneath, the request-building code for side-queries now accepts an effort option that becomes output_config.effort on the API call; if a model rejects it, Claude Code remembers the model doesn't support it and retries without the field, logging a telemetry event.
Why
This lets you run Claude Code at maximum effort and know at a glance when that mode is active, via /effort to change it, while the underlying request logic gracefully falls back for models that don't support the effort parameter.
Nothing here resolved what this flag was doing on this version, so nothing here should be read as on or off.
This account: no value returned · anonymous baseline: no value returned · compiled default in v2.1.280: off
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.
The entry above is what we published on the day. These lines were added later, as Anthropic's own pages caught up, and they sit beside the original rather than replacing it.
Added sinceA small documentation edit on Orchestrate subagents at scale with dynamic workflows touched a line naming /effort after this was published.When workflows are disabled, the bundled workflow commands and the `/workflow-authoring` skill are unavailable, the `ultracode` keyword no longer triggers a run, and `ultracode` is removed from the `/effort` menu. A run that was already in…workflowssee the edit
Confirmed sinceAnthropic's documentation has since written up /effort, on prompting-claude-opus-5.Claude Opus 5 runs with [thinking](https://platform.claude.com/docs/en/build-with-claude/thinking) on by default, and thinking can be disabled only at [effort](https://platform.claude.com/docs/en/build-with-claude/effort) `high` or below. …build-with-claude/prompt-engineering/prompting-claude-opus-5see the edit
How sure we are
Two sources agreeTwo things we can check say the same as this entry.
Anthropic's documentation agreesAnthropic's documentation has since written up /effort, on prompting-claude-opus-5.
Anthropic's release notes agreeFixed Ctrl+C or Ctrl+D pressed twice in most dialogs (/model, /effort, /config, /status, /usage, /plugin, /sandbox, /permissions…
The name it cites is new in this buildNew in this build: CLAUDE_CODE_MAX_EFFORT_REMINDER
