CLAUDE_CODE_WEB_SEARCH_FAST_ARG
A Claude Code environment variable, read out of the shipped bundle. It has been in the build since v2.1.282, including the newest one read.
The web search tool has a built-in choice between a quick, cheap search and a slower, thorough one, but it stays off unless configured
Not Anthropic's. This is the line from the earliest changelog entry here that named it, v2.1.282.
In the changelogs
4Releases whose published page names CLAUDE_CODE_WEB_SEARCH_FAST_ARG.
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v2.1.283
Setting the web-search proxy variable no longer turns off fast web search
CLAUDE_CODE_WEBSEARCH_USE_CCR_PROXYno longer forces fast web search off, andCLAUDE_CODE_WEBSEARCH_CCR_PROXY_FASTis gonefound in this entry's text
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v2.1.282
Web search can offer a quick "standard" mode and a thorough "extended" mode, off by default
The web search tool has a built-in choice between a quick, cheap search and a slower, thorough one, but it stays off unless configured
found in this entry's text
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v2.1.282
Fast web search can add an extra hint to Claude's instructions
When fast web search is on and a web search tool is available, Claude's system prompt gets an extra hint
found in this entry's text
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v2.1.282
Web search instructions can be extended remotely, and a stray option is ignored
When fast web search is enabled, extra WebSearch tool instructions can be supplied remotely, and a
modevalue sent while it is off is droppedfound in this entry's text
First cited
0No release's published evidence quotes this name. The ledger indexes the Evidence lines of every changelog on this site, so this says nobody here has ever quoted it; it says nothing about how old the name is.
Presence across releases
1Build by build
37One row per release since the first build this name was read out of. Absent means the build was read and the name was not in it, never mined means no bundle for that release was ever archived, and a declared type or a default is only ever what that release's own bundle stated.
Read out of the published npm bundle release by release, and out of Anthropic's own documentation as this site captured it. Nothing on this page is a description anybody here wrote about what the environment variable does. All environment variables.