MAX_MCP_OUTPUT_TOKENS
A Claude Code environment variable, read out of the shipped bundle. It was in the build from v2.1.138 and was gone by v2.1.242.
What it is
Nonsense values in retry, MCP output and hook timeout env vars now fall back to defaults.
Not Anthropic's. This is the line from the earliest changelog entry here that named it, v2.1.228.
Presence across releases
| Releases | Reading | Declared type | Default |
|---|---|---|---|
| 2.1.245 – 2.1.250 5 releases | never mined | — | — |
| 2.1.242 – 2.1.243 2 releases | not in the build | — | — |
| 2.1.160 – 2.1.241 73 releases | in the build | int | — |
| 2.1.138 – 2.1.159 20 releases | in the build | — | — |
A row reading never mined is a release with no archived bundle behind it. Nothing was read out of it, so nothing here says whether the name was in it. A declared type or a default is only ever what that release's own bundle stated.
Changelog entries naming it
-
v2.1.248MCP output token cap resolution
MAX_MCP_OUTPUT_TOKENS is still honoured first, but it's no longer sanity-checked as a number.
named in this entry
-
v2.1.228Garbage numeric env vars fall back to defaults
Nonsense values in retry, MCP output and hook timeout env vars now fall back to defaults.
named in this entry
Documentation pages
- Connect to external tools with MCP mentions it Claude Code CLI
- Connect Claude Code to tools via MCP mentions it Claude Code CLI
- Building custom connectors mentions it Claude Documentation
- Troubleshooting MCP Apps mentions it Claude Documentation
A reference table page is one whose own table defines this name, and it is where the description above came from. A page that mentions it carries the name somewhere in its text and may say nothing about it at all. Every page carrying it.
Names beside it
Every environment variable in the inventory starting max, up to twelve of them.
MAX_STRUCTURED_OUTPUT_RETRIESNo description from anybody. 2.1.138
MAX_THINKING_TOKENSYou now get told when an effort level needs thinking on, and what turned thinking off. 2.1.138
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.