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 v2.1.257 ·

Mid-conversation tool-change surfacing to the model, gated off by default

Tools added or removed mid-conversation can be surfaced to the model, but the beta capability is gated off by default.

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Tools added or removed mid-conversation can be surfaced to the model, but the beta capability is gated off by default.

New logic lets the assistant see tools added or removed mid-conversation via a fresh system turn re-normalized with surfaceLateToolAdditions, instead of only picking up tool changes at the start of a turn. Message normalization gains a toolChangeFallback path and a blocksEligible flag, but the behavior only activates when the beta capability mid_conv_tool_change is included in the request, which itself requires a Statsig-style gate to pass plus per-model eligibility, so it's gated off by default.

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The name it cites is new in this buildNew in this build: tengu_mossy_lantern

See this entry in the whole of v2.1.257 →