biome explain: Look Up Rules and Diagnostics
biome explain prints the documentation for a named lint rule or daemon-logging topic without leaving the terminal.
When CI fails on a rule you do not recognize, explain gives you the rule description and rationale right where you are, instead of opening the website.
What it does
biome explain takes the name of a lint rule (or a special topic like daemon-logs) and prints its documentation, including what it catches and why. It is a read-only command that does not touch your files or config.
Common usage
npx @biomejs/biome explain noExplicitAny
npx @biomejs/biome explain noUnusedVariables
# print where the daemon writes its logs
npx @biomejs/biome explain daemon-logsOptions
| Argument | What it does |
|---|---|
| <ruleName> | Print documentation for that lint rule |
| daemon-logs | Print the daemon log file location |
In CI
explain is mainly a local debugging aid; you will rarely run it in a pipeline. When a CI log shows an unfamiliar rule, run biome explain <rule> on your machine to understand the diagnostic before deciding to fix the code or adjust config.
Common errors in CI
"Unknown rule" means a misspelling or a rule that does not exist in the installed version; check the version and the exact name from the CI diagnostic. The rule name passed to explain is the short name (noExplicitAny), not the full path (lint/suspicious/noExplicitAny).