Debugging eats more engineering time than writing new code. The hard part is rarely fixing the bug — it’s finding it. Tracing a 500 error through three services, figuring out why a payload that worked yesterday returns a 422 today, or understanding why a function behaves differently in staging than in production. Agent skills for debugging take over the mechanical investigation work so you can focus on the fix.

These five skills cover different phases of the debugging lifecycle: catching bugs before merge, diagnosing API failures, investigating production incidents, scanning for hidden vulnerabilities, and reproducing issues with generated test cases.

What to look for

Diagnostic depth is the first filter. A debugging skill should not just tell you something is broken. It should tell you why, point to the specific line or request that caused the failure, and suggest a fix. “Test failed” is useless. “This function returns null when the input array is empty because the guard clause on line 47 checks length > 0 instead of length >= 0” is useful.

Context awareness matters. The best debugging skills read your project structure, understand your framework conventions, and factor in your dependency versions when diagnosing problems. A skill that doesn’t know you’re running Express 5 will waste your time suggesting Express 4 solutions.

Speed of feedback separates practical tools from impressive demos. If a debugging skill takes five minutes to analyze a single file, you’ll stop using it after the first session. The useful ones return results in seconds, fast enough to stay in your flow.

Finally, look at reproducibility. The best debugging skills don’t just identify the problem — they help you prove it exists with a test case or reproduction step that you can run again after the fix.

Top agent skills for debugging and troubleshooting

1. API Debugger

API Debugger diagnoses failing API calls by analyzing the full request/response pair: headers, status codes, payloads, and timing. When something returns a 400 or a 500, this skill figures out whether the problem is your auth header, your payload schema, a rate limit, or the upstream service itself.

The real value shows up with intermittent failures. Those 502s that only happen under load, the timeouts that come and go, the auth tokens that expire at unpredictable intervals — API Debugger looks at the timing data and request patterns to identify what’s actually going wrong. It separates “your code is sending bad requests” from “the upstream service is flaky” so you stop chasing the wrong root cause.

Compatible with: Claude Code, Codex, Cursor Category: Engineering Install: gh skill install sickn33/antigravity-awesome-skills/api-debugger

2. Incident Responder

Incident Responder runs structured incident response using ITIL and SRE runbook patterns. It handles triage, root cause analysis, mitigation steps, and post-mortem drafting. When production breaks at 2 AM, this skill walks the agent through a systematic investigation instead of letting it flail.

The structure is what makes it valuable. Panicked debugging in production skips steps. Incident Responder enforces a sequence: assess impact, identify the blast radius, check what changed recently, isolate the failing component, apply mitigation, then dig into root cause. It also drafts the post-mortem while the investigation is fresh, which means the post-mortem actually gets written instead of becoming a task that nobody finishes.

Compatible with: Claude Code, Codex Category: Engineering Install: gh skill install ComposioHQ/awesome-claude-skills/incident-responder

3. Code Reviewer

Code Reviewer performs structured code review focused on finding bugs, not enforcing style. It identifies potential null pointer errors, unhandled promise rejections, N+1 query patterns, logic errors in conditional branches, and security issues. Each finding gets a severity rating and a suggested fix.

For debugging specifically, Code Reviewer works best as a preventive tool. Run it before merge and it catches the bugs that would otherwise become production incidents. But it’s also useful after the fact: point it at a module where you suspect a bug and it surfaces the likely candidates faster than reading through every function manually. The severity ratings help you prioritize — fix the critical path bugs first, address the edge cases later.

Compatible with: Claude Code, Codex, Cursor, Windsurf Category: Engineering Install: gh skill install wshobson/agents/code-reviewer

4. Security Auditor

Security Auditor scans codebases for vulnerabilities that cause a specific category of bugs: the ones you don’t find until someone exploits them. Exposed secrets, SQL injection, XSS, insecure dependencies, and OWASP Top 10 patterns. It returns a prioritized report with severity ratings and remediation steps.

Security bugs are debugging problems with higher stakes. A null pointer crashes the page. An SQL injection leaks your user table. Security Auditor treats the codebase as an attack surface and systematically tests for the patterns that lead to breaches. It’s not a penetration test, but it catches the low-hanging vulnerabilities that account for most real-world incidents. Pair it with Code Reviewer for a combined pass that covers both logic bugs and security holes.

Compatible with: Claude Code, Codex, Cursor Category: Security Install: gh skill install wshobson/agents/security-auditor

5. Test Generator

Test Generator produces tests from existing code, including edge cases and error paths. For debugging, the use case is specific: once you find a bug, you need a test that reproduces it before you fix it. Test Generator creates that reproduction test so you can verify the fix and prevent the regression.

It’s also useful for proactive debugging. Point it at a module and let it generate edge-case tests. When those tests fail, you’ve found bugs you didn’t know existed. The boundary condition tests — empty inputs, max-length values, concurrent operations — tend to expose the kinds of issues that only surface in production under real traffic patterns. Supports Jest, pytest, Vitest, and Go’s testing package.

Compatible with: Claude Code, Codex, Cursor, Windsurf Category: Engineering Install: gh skill install sickn33/antigravity-awesome-skills/test-generator

How to choose

Match the skill to where your bugs actually come from. If most of your issues are API integration failures — bad payloads, auth problems, upstream timeouts — start with API Debugger. If your production incidents are chaotic and your post-mortems never get written, Incident Responder adds the structure you need.

For preventive debugging, Code Reviewer and Security Auditor run together as a pre-merge gate. They catch different classes of bugs: Code Reviewer finds logic errors, Security Auditor finds exploitable vulnerabilities. Running both is more effective than running either alone.

Test Generator is the bridge between finding a bug and proving it’s fixed. Use it after any debugging session to lock down the reproduction case so the same bug doesn’t come back in a future refactor.

The practical stack for most teams: Code Reviewer and Security Auditor before merge, API Debugger and Incident Responder when things break, Test Generator to close the loop with a regression test.

FAQ

Q: How do these skills compare to traditional debugging tools like Chrome DevTools or pdb? A: They work at a different level. DevTools and pdb are interactive debuggers that you operate manually. These skills automate the investigation phase — analyzing code, tracing request failures, and identifying patterns across a codebase. Use them alongside your debugger, not instead of it. The skill narrows the search space; the debugger confirms the root cause.

Q: Can Incident Responder actually help during a live production incident? A: Yes, with a caveat. It provides structure and drafts analysis in real time, but it can only work with the information the agent has access to. If your logs and metrics are accessible to the agent (via MCP servers or file access), it can triage effectively. If the relevant data is locked behind a VPN or dashboard with no API, you’ll need to paste the relevant context manually.

Q: Do I need separate skills for frontend and backend debugging? A: Not necessarily. API Debugger handles HTTP-layer problems regardless of which side generated them. Code Reviewer and Test Generator work with any language the agent supports. The one exception is browser-specific debugging — for that, pair these skills with Web App Tester, which handles Playwright-based E2E testing and captures screenshots of UI failures.