Claude.ai Quietly Rolls Out Undocumented web_search_fast Tool

tedbradly · reddit · 2026-09-18

A Reddit user who logs all of Claude's tool calls discovered an undocumented websearchfast tool in his claude.ai session — with zero press coverage or release notes anywhere.

Per Claude's own system-prompt description, it's a lightweight, cheaper, faster variant of websearch: same interface (one query string), returning up to 10 results with title, URL, and excerpt. The design is two-tier: default to the fast variant for simple lookups, escalate to the heavier websearch when results are thin, off-target, or stale — and go straight to the full version for hard-to-find, time-sensitive, price-sensitive, or multi-step research queries.

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