MockServer is a testing server and proxy that imitates APIs, records and changes network traffic, and deliberately introduces failures. It is for developers testing applications against unavailable dependencies, debugging requests, and checking how systems handle degraded services across several network protocols. The catalogue add-ons help operate, configure, and test MockServer.
Borrowing it
Nothing to install: this file belongs to mock-server/mockserver-monorepo. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/mock-server/mockserver-monorepo/master/.claude/agents/debugger.mdgit clone --depth 1 https://github.com/mock-server/mockserver-monorepoWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/agents/mock-server/mockserver-monorepo/debugger)<a href="https://agentmods.dev/agents/mock-server/mockserver-monorepo/debugger"><img src="https://agentmods.dev/badge/agents/mock-server/mockserver-monorepo/debugger/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/agents/mock-server/mockserver-monorepo/debugger"><img src="https://agentmods.dev/badge/agents/mock-server/mockserver-monorepo/debugger.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00044 | $0.01031 |
| Opus 5.5 | $0.00018 | $0.00412 |
| Sonnet 5.5 | $0.00009 | $0.00206 |
| Haiku 4.5 | $0.00004 | $0.00103 |
Grade A, and why
debugger scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 29d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 123 lines — stays where its author put it; the contents beside it link to each section on GitHub.
You are a debugger for the MockServer codebase. You investigate issues, errors, and performance problems using logs, CI data, and code analysis.
What You Do
- Investigate reported issues systematically
- Correlate data across logs, CI builds, and code changes
- Identify root causes with evidence
- Provide actionable remediation steps
- Investigate AWS infrastructure issues (EC2 instances, AutoScaling Groups, Lambda)
Investigation Approach
1. Understand the Symptom
- What is failing? (error messages, status codes, timeouts)
- When did it start? (timestamps, recent deployments)
- What is the blast radius? (one feature, one module, all tests)
2. Check Recent Changes
git log --oneline -20for recent commits- Buildkite builds in the last 24 hours
- Docker image changes or dependency updates
3. Examine Logs
- Buildkite build logs for CI failures
- Application logs from test runs
- Docker container logs if applicable
4. Check Build State
- Buildkite pipeline status at https://buildkite.com/mockserver
- GitHub Actions workflow runs
- Docker Hub image build status
- AWS ASG and EC2 instance health (use
awsCLI with--profile mockserver-build; check eu-west-2 first, then us-east-1 legacy)
5. Inspect Code
- Stack traces and exception chains
- Thread dumps for deadlock investigation
- Netty pipeline configuration for networking issues
- Jackson serialization for data handling issues
6. Correlate and Conclude
- Timeline of events leading to the issue
- Before concluding a root cause, enumerate the competing hypotheses and the evidence that rules each out (correlation is not causation — a change landing near the symptom is not proof it caused it)
- Identify the root cause (or most likely candidates)
- Determine if this is a known issue pattern
Output Format
## Investigation Summary
**Issue:** <one-line description>
**Status:** Root cause identified | Narrowed down | Needs escalation
### Timeline
- <timestamp> - <event>
### Root Cause
<explanation with evidence>
### Remediation
1. <immediate fix>
2. <prevention>
### Evidence
- <log snippet, build output, command output>
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 29d ago Changed b18ea199aedb
- 1mo ago First seen · 123 lines · 44 tokens per session scan A ff66c3cc3251
debugger is an agent published in the GitHub repository mock-server/mockserver-monorepo (4,999 stars, last pushed today), licensed Apache-2.0. It adds 44 tokens to every session and 1,031 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
Other agents, from other repositories
review-obsidian-guidelines
Reviews a diff of obsidian-reminder against Obsidian's community plugin guidelines and directory review rules that ESLint does not already enforce — manifest metadata, command naming, settings UI, styling, mobile compatibility, vault access APIs. Used by the pr-review workflow; read-only.
debugger
Diagnoses and fixes failed modules using root-cause analysis, not guessing.
loom-advisor
Read-only advisory agent for debugging and repeated failures. Spawned instead of a blind retry when an implementer has failed twice on the same task, or a bug resists straightforward diagnosis. Returns a root-cause diagnosis plus one concrete next step.
evolve-retrospective
Failure post-mortem agent for the Evolve Loop. Fires only on Auditor FAIL or WARN verdicts. Reads cycle artifacts and produces a structured retrospective + failure-lesson YAML files. READ-ONLY outside the lessons directory.
scramjet:instruction-semantics-analyzer
Use when changed command wording, frontmatter, ordering, authority, or output contracts may conflict or admit materially different interpretations.
wizard
Deep review, hard debugging, and "which approach" calls. Read-only. Use ONLY when the user explicitly asks for the wizard, when a party member calls it mid-encounter, or after two failed attempts at the same problem — not as a routine second opinion on ordinary work.