Sweep 19 Sep 2026 · 02:36Z Build v2.1.278 500 read Stable v2.1.267 Latest v2.1.278 Next v2.1.278 Feeds RSS JSON llms.txt Unofficial
Claude Code v2.1.275 ·

tool.call hook-event schema gains a measure combinator

The tool.call hook event gained a 'measure' step that combines context across related events

TierUnder the hoodhow much it should matter to you
Useful1my rating, 1 to 5
Signal1worth watching, 1 to 5
AreaHookswhat it touches
KindInternal Changesin v2.1.275,
Under the hood

The tool.call hook event gained a 'measure' step that combines context across related events

What

The internal descriptor for the tool.call hook event, used alongside PreToolUse (a hook point that runs before a tool call executes and can block it), now includes a measure function. This function combines the context of one event with the contexts of a list of related events, replacing what was previously a simpler carry function.

Why

This is internal plumbing for how hook event context is assembled; the finding doesn't indicate a directly user-visible change.

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Names in the bundletool.call
What the documentation says
How sure we are
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubtWhat practical difference the new 'measure' combinator makes to hook authors versus the previous 'carry' function is not stated.

See this entry in the whole of v2.1.275 →