OpenTelemetry Tracing Support (Opt-In) / Claude Code v2.0.18

What: Comprehensive distributed tracing infrastructure for monitoring Claude Code's internal operations, API calls, and performance metrics. This feature is disabled by default and requires explicit opt-in.

How to use:

# Enable telemetry
export CLAUDE_CODE_ENABLE_TELEMETRY=true

# Configure where traces are exported (optional)
export OTEL_TRACES_EXPORTER=console  # or "otlp" for OpenTelemetry collectors

# Privacy controls (optional - both default to redacted)
export OTEL_LOG_USER_PROMPTS=true     # Log user prompts in traces
export OTEL_LOG_MODEL_RESPONSE=true   # Log model responses in traces

Details:

Tracks user interactions, LLM API requests/responses, and tool executions
Privacy-conscious by default: User prompts and model responses are redacted unless explicitly enabled via OTEL_LOG_USER_PROMPTS and OTEL_LOG_MODEL_RESPONSE
Supports multiple export formats:
console - Output traces to console for debugging
otlp - Export to OpenTelemetry Protocol collectors (supports gRPC, HTTP/JSON, HTTP/Protobuf)
Records detailed metrics: token counts (input, output, cache read, cache creation), latency, success/failure rates
Full OpenTelemetry specification compliance with 15+ configuration environment variables
Configurable sampling strategies via OTEL_TRACES_SAMPLER (defaults to parentbased_always_on)
Batch span processor with tunable performance parameters
Evidence: DiB() at line 2314, JiB() at line 2048, Jb0() at line 2087, cL5() at line 2277

Supported Environment Variables:

Telemetry Control:

CLAUDE_CODE_ENABLE_TELEMETRY - Master switch (default: disabled)
OTEL_LOG_USER_PROMPTS - Include user prompts in traces (default: redacted)
OTEL_LOG_MODEL_RESPONSE - Include model responses in traces (default: redacted)

Export Configuration:

OTEL_TRACES_EXPORTER - Exporters: "console", "otlp" (comma-separated)
OTEL_EXPORTER_OTLP_TRACES_PROTOCOL - Protocol: "grpc", "http/json", "http/protobuf"
OTEL_EXPORTER_OTLP_PROTOCOL - Default protocol for all signals

Sampling:

OTEL_TRACES_SAMPLER - Sampler type (default: "parentbased_always_on")
OTEL_TRACES_SAMPLER_ARG - Sampler configuration (e.g., ratio for TraceIdRatioBased)

Span Limits:

OTEL_ATTRIBUTE_VALUE_LENGTH_LIMIT - Max attribute value length (unlimited by default)
OTEL_ATTRIBUTE_COUNT_LIMIT - Max attributes per span (default: 128)
OTEL_SPAN_ATTRIBUTE_VALUE_LENGTH_LIMIT - Span-specific attribute value limit
OTEL_SPAN_ATTRIBUTE_COUNT_LIMIT - Span-specific attribute count (default: 128)
OTEL_SPAN_LINK_COUNT_LIMIT - Max links per span (default: 128)
OTEL_SPAN_EVENT_COUNT_LIMIT - Max events per span (default: 128)
OTEL_SPAN_ATTRIBUTE_PER_EVENT_COUNT_LIMIT - Max attributes per event (default: 128)
OTEL_SPAN_ATTRIBUTE_PER_LINK_COUNT_LIMIT - Max attributes per link (default: 128)

Batch Processor:

OTEL_BSP_MAX_EXPORT_BATCH_SIZE - Batch size (default: 512)
OTEL_BSP_MAX_QUEUE_SIZE - Queue size (default: 2048)
OTEL_BSP_SCHEDULE_DELAY - Export delay in ms (default: 5000)
OTEL_BSP_EXPORT_TIMEOUT - Timeout in ms (default: 30000)

See this entry in the whole of v2.0.18 →

The build it came inv2.0.18

15 Oct 2025 · 5 entries, this one is #1.

Either side of it

v2.0.17Older
v2.0.19Newer

Open the release →

Names in this entry

envOTEL_LOG_USER_PROMPTS
Remote-session telemetry now redacts prompts, model names and agent ids when sending traces off-box
envCLAUDE_CODE_ENABLE_TELEMETRY
Set to 1 to enable OpenTelemetry data collection for metrics and logging. Required before configuring OTel exporters. Set it in your shell, user settings, or managed settings. Ignored in project and local settings. See Monitoring
envOTEL_TRACES_EXPORTER
Telemetry export can now send metrics, logs, and traces to different destinations instead of forcing all three to OTLP
envOTEL_EXPORTER_OTLP_TRACES_PROTOCOL
You can now set standard OpenTelemetry compression and per-signal protocol variables and have them respected.
envOTEL_EXPORTER_OTLP_PROTOCOL
OTLP transport for Claude Code's telemetry exporters (metrics, logs and traces) when the signal-specific OTEL_EXPORTER_OTLP_<SIGNAL>_PROTOCOL variable is empty. Accepted values are grpc, http/json and http/protobuf; any other value, including leaving both unset, makes exporter setup throw Unknown protocol set in ... env var, and for traces one code path forces http/protobuf regardless. The claude gateway server also sets it to http/protobuf in the environment it pushes to clients through managed settings when telemetry.forward_to and listen.public_url are configured.
envOTEL_ATTRIBUTE_VALUE_LENGTH_LIMIT
Claude Code caps the content it records in telemetry (prompts, system prompts, model output, tool inputs and results) at the smallest of this, OTEL_LOGRECORD_ATTRIBUTE_VALUE_LENGTH_LIMIT, OTEL_SPAN_ATTRIBUTE_VALUE_LENGTH_LIMIT and CLAUDE_CODE_OTEL_CONTENT_MAX_LENGTH (default 61440), cutting longer content and appending a [TRUNCATED - Content exceeds ... limit] marker. The bundled OTel SDK reads it only as a fallback for the log record and span attribute limits, which its own defaults always fill (unlimited when their variables are unset), so it does not limit SDK attributes.
envOTEL_SPAN_ATTRIBUTE_VALUE_LENGTH_LIMIT
Maximum length of span attribute values in the bundled OpenTelemetry trace SDK; unset means no limit. Claude Code also uses the smallest of this, OTEL_ATTRIBUTE_VALUE_LENGTH_LIMIT, OTEL_LOGRECORD_ATTRIBUTE_VALUE_LENGTH_LIMIT and CLAUDE_CODE_OTEL_CONTENT_MAX_LENGTH (default 61440) as the character cap on the content it records in telemetry, such as prompts, system prompts, model output and tool inputs and results.

Is this right?