Source Intelligence

DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.

All of v2.1.223 Home All releases olderv2.1.222 v2.1.224newer

New prompt-variant experiment for two tools

Not switched on
Useful2 Signal3
Agents Notable not in their notes

An alternate prompt wording for two tools exists but stays off unless you set an environment variable.

Alternate tool prompt variants sit behind CLAUDE_CODE_PARCHMENT_FERN and a gate defaulting to false.

Feature flag
tengu_parchment_fern Off in both readings

The flag server returned off for the account this site reads and for the anonymous baseline. A reading of off cannot rule out a rollout these two readings sit outside of.

This account: off · anonymous baseline: off · compiled default in v2.1.223: 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.

tengu_velvet_mallet Off in both readings

The flag server returned off for the account this site reads and for the anonymous baseline. A reading of off cannot rule out a rollout these two readings sit outside of.

This account: off · anonymous baseline: off · compiled default in v2.1.223: 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.

Read once, for one account on one subscription tier, against v2.1.223. It isn't a statement about your account. What a flag value here can and cannot tell you

CLAUDE_CODE_PARCHMENT_FERN
What

Two model-scoped predicates were added that swap in an alternate prompt variant for their tools. Off by default in this build.

Details
  • Enabled by the environment variable CLAUDE_CODE_PARCHMENT_FERN, a per-model opus_5_prompt_bundle capability, a settings key, or the gate tengu_parchment_fern, which falls back to false.
  • One of the two predicates is additionally conditioned on the existing per-model tengu_velvet_mallet gate.
  • When active, the variants appear as marker prefixes in the prompt-cache key.
Evidence

tengu_parchment_fern

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

See this entry in the whole of v2.1.223 →