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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 v2.1.217 Home All releases ←olderv2.1.216 v2.1.218newer→
Claude Code v2.1.217

tengu_heron_tallow — New Feature Gate [Feature-Flagged]

Feature flag
tengu_heron_tallow 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 v2.1.217: 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 v2.1.217. It isn't a statement about your account. What a flag value here can and cannot tell you

What

A new feature flag tengu_heron_tallow is available. It can also be enabled via the CLAUDE_CODE_HERON_TALLOW environment variable or via managed settings.

Status

Feature-flagged (also overridable via CLAUDE_CODE_HERON_TALLOW env var)

Details
  • Ohd() returns true if Z.CLAUDE_CODE_HERON_TALLOW env var is truthy, the managed settings object has tengu_heron_tallow: true, or the feature flag is on via Ke()
  • Ohd() is called inside mks(), which generates the hint text appended to tool-not-found errors in the model context when a tool call cannot be routed to any registered tool
  • When Ohd() is true and the tool name resolves to an existing-but-not-enabled tool: the hint changes from "X exists but is not enabled in this context. Use one of the available tools instead." to "X is disabled for this session, in subagents as well as here."
  • When Ohd() is true and the tool is in the known-but-session-unavailable set (sat()): the hint changes from "X is not available in this context. Use one of the available tools instead." to "X is disabled for this session."
  • The change shifts the model's framing from "try a different tool" toward "this tool is a session-level prohibition", which may affect how the model responds to tool-call failures in restricted sessions
Evidence

Ohd() function (search for "CLAUDE_CODE_HERON_TALLOW") and its changed hint strings (search for "is disabled for this session, in subagents as well as here")

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

See this entry in the whole of v2.1.217 →