Building Skills for Claude — Complete Guide

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Course content

4.3 Error Handling

Error Handling in Skills

Make your Skills robust and fault-tolerant

Robust Skills handle the unexpected gracefully. Planning for errors is what separates amateur Skills from production-ready ones.

Error Handling Strategies

Add Fallback Instructions

Tell Claude what to do when something goes wrong. Never let a skill fail silently.

Tell Claude When to Ask

If information is missing, Claude should ask instead of guessing. Guessing leads to wrong outputs.

Include Validation Checks

Have Claude verify its own output before presenting it. Self-validation catches most errors.

Handle Missing Inputs

Not every user provides perfect information. Plan for incomplete, malformed, or missing data.

Error Handling Template

## Common Issues

### MCP Connection Failure
If you see "Connection refused":
1. Verify that the MCP server is running
2. Confirm that the API key is valid
3. Try reconnecting: Settings > Extensions > Reconnect

### Missing Data
If required fields are empty:
1. Ask the user which fields to fill in
2. Suggest default values where appropriate
3. Never proceed with critical missing data

Defensive Instructions

Always include a 'what if' section in your Skill. For every step that could fail, write what Claude should do instead.

Error Handling Rule

A Skill without error handling is a Skill waiting to fail. Cover the top 3-5 most likely failure modes, and your Skill will handle 95 percent of real-world situations gracefully.