Cloudflare Workers Observability

Debug and monitor Cloudflare Workers using logs and analytics from the Observability MCP server.

Available Tools

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

Debugging Workflow

1. Identify the problem

   • Query recent errors with query_worker_observability

2. Find patterns

   • Use observability_keys to discover relevant fields
   • Use observability_values to see error types

3. Narrow down

   • Add filters for specific routes, times, or status codes

4. Analyze specific invocations

   • Query for detailed logs of problematic requests

Post-Deployment Monitoring

After deploying, check for issues:

1. Query for errors in the last 5-10 minutes
2. Compare error rates before/after deployment
3. Check latency metrics for performance regression

Tips

• Start broad, then add filters to narrow results
• Use observability_keys when unsure what fields exist
• Custom console.log output appears in queryable fields
• Combine with builds tools to correlate issues with deployments