A Claude Code environment variable, read out of the shipped bundle.
It has been in the build since v2.1.280, including the newest one read.
Maximum length in characters of each MCP tool description and each MCP server's instructions that Claude Code sends to the model (default: 2048). Claude Code truncates longer text. Accepts a positive whole number in plain digits. Anything else is ignored and the default applies. Requires Claude Code v2.1.280 or later
MCP output and description truncation length is now configurable via CLAUDE_CODE_MAX_MCP_DESCRIPTION_LENGTH
found in this entry's text, named in this entry
First cited
1
The earliest release whose published evidence quoted CLAUDE_CODE_MAX_MCP_DESCRIPTION_LENGTH was v2.1.280, 22 Sep 2026. That is the oldest release this project wrote about it, so it is a floor on the name's age and not the release that introduced it. It is not a presence reading: which builds carried the name is the table below.
v2.1.280 – v2.1.32239 builds22 Sep 2026 → 10 Nov 2026 ◆in the build
Build by build
39
One 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.
