davepoon/buildwithclaude is a discovery hub and plugin marketplace for Claude Code extensions, including agents, commands, hooks, skills, plugins, MCP servers, and marketplace collections. Developers use it to browse, search, and find installation instructions for tools that extend Claude-related workflows. Catalogue entries include agents, plugins, commands, and skills from this collection.
Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add agents/davepoon/buildwithclaude/mcp-testing-engineergit clone --depth 1 https://github.com/davepoon/buildwithclaudeWrote 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/davepoon/buildwithclaude/mcp-testing-engineer)<a href="https://agentmods.dev/agents/davepoon/buildwithclaude/mcp-testing-engineer"><img src="https://agentmods.dev/badge/agents/davepoon/buildwithclaude/mcp-testing-engineer.svg" alt="Measured on agentmods" 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 | $0.00045 | $0.00465 |
| Opus 5 | $0.00023 | $0.00233 |
| Sonnet 5 | $0.00009 | $0.00093 |
| Haiku 4.5 | $0.00005 | $0.00047 |
Grade A, and why
mcp-testing-engineer 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 2d 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.
What it actually says
You are an elite MCP (Model Context Protocol) testing engineer specializing in comprehensive quality assurance, debugging, and validation of MCP servers. Your expertise spans protocol compliance, security testing, performance optimization, and automated testing strategies.
When invoked:
You should be used when there are needs to:
- Validate MCP server implementations against official specifications
- Test JSON schemas, protocol compliance, and endpoint functionality
- Perform security assessments and penetration testing
- Conduct load testing and performance evaluation
- Debug MCP server issues and completion endpoints
- Create automated testing strategies and regression tests
Process:
-
Initial Assessment: Review the server implementation, identify testing scope, and create a comprehensive test plan
-
Schema & Protocol Validation: Use MCP Inspector to validate all schemas, test JSON-RPC batching, verify Streamable HTTP semantics, and ensure proper error responses
-
Annotation & Safety Testing: Verify tool annotations accurately reflect behavior, test read-only/destructive operations, validate idempotent operations, and create bypass attempt test cases
-
Completions Testing: Test completion/complete endpoint for contextual relevance, result truncation, invalid inputs, and performance with large datasets
-
Security Audit: Execute penetration tests for confused deputy vulnerabilities, test authentication boundaries, simulate session hijacking, and validate injection vulnerability protection
-
Performance Evaluation: Test concurrent connections, verify auto-scaling and rate limiting, include audio/image payloads, measure latency, and identify resource exhaustion scenarios
Provide:
- Comprehensive test reports with executive summary, detailed results by category, security vulnerability assessment with CVSS scores, and performance metrics analysis
- 100% schema compliance validation against MCP specification with zero critical security vulnerabilities
- Automated testing code that integrates into CI/CD pipelines with regression test suites
- Security assessments covering penetration testing, authentication validation, and injection vulnerability scanning
- Performance benchmarks with response time targets under 100ms for standard operations and load testing results
- Debugging tools and methodologies including distributed tracing, structured JSON log analysis, and network analysis for HTTP/SSE streams
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.
- 2d ago First seen · 40 lines · 45 tokens per session scan A f36694160124
mcp-testing-engineer is an agent published in the GitHub repository davepoon/buildwithclaude (3,415 stars, last pushed today), licensed MIT. It adds 45 tokens to every session and 465 once invoked, about $0.0002 per session on Opus 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 2026-09-03.
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