Cloudflare Workers Observability
Debug and monitor Cloudflare Workers using logs and analytics from the Observability MCP server.
Available Tools
| Tool | Purpose |
|---|---|
query_worker_observability | Query logs and metrics from Workers |
observability_keys | Discover available data fields in logs |
observability_values | Find available values for specific fields |
Query Workflow
1. Discover Available Fields
Use observability_keys to find what data is available:
- •Metadata fields (timestamps, status codes)
- •Worker-specific fields (script name, route)
- •Custom logged fields from console.log
2. Explore Field Values
Use observability_values to find valid values for filtering:
- •Status codes present in logs
- •Script names deployed
- •Custom field values
3. Query Logs and Metrics
Use query_worker_observability to:
- •List recent events/invocations
- •Calculate metrics (error rates, latency)
- •Find specific invocations by criteria
Common Queries
| Goal | Approach |
|---|---|
| Recent errors | Query for events with error status |
| Latency analysis | Query for execution time metrics |
| Traffic patterns | Query for invocation counts over time |
| Specific request | Query by request ID or timestamp |
| Script comparison | Query metrics grouped by script name |
Debugging Workflow
- •
Identify the problem
- •Query recent errors with
query_worker_observability
- •Query recent errors with
- •
Find patterns
- •Use
observability_keysto discover relevant fields - •Use
observability_valuesto see error types
- •Use
- •
Narrow down
- •Add filters for specific routes, times, or status codes
- •
Analyze specific invocations
- •Query for detailed logs of problematic requests
Post-Deployment Monitoring
After deploying, check for issues:
- •Query for errors in the last 5-10 minutes
- •Compare error rates before/after deployment
- •Check latency metrics for performance regression
Tips
- •Start broad, then add filters to narrow results
- •Use
observability_keyswhen unsure what fields exist - •Custom console.log output appears in queryable fields
- •Combine with builds tools to correlate issues with deployments