What
Telemetry is the usage and performance data Claude Code can report, here through OpenTelemetry (OTEL), a common standard for that data. Labels you define for it are now checked against these rules:
- Names: 1 to 255 characters, using only letters, digits,
.,_and-. - Reserved names:
service.name,service.version,claude.deployment_mode,host.arch,os.type,os.versionandwsl.versioncannot be used. - Reserved prefixes: names starting with
enduser.,user.oridentity.cannot be used. - Values: must not be empty, must use printable ASCII characters only, and must fit in 255 characters once encoded.
Using a reserved name gives an error saying the gateway or Claude sets it and asking you to choose another name.
Why
Your own labels can no longer overwrite the ones Claude Code or a gateway sets. Anyone who already sends custom labels should check them against these rules.
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubt
The finding does not say which setting defines these labels or what happens to existing labels that fail the check.