HN Showcase
Back to browse
MCPSpec – Ship reliable MCP servers without writing test code

MCPSpec – Ship reliable MCP servers without writing test code

by warmcat·Feb 25, 2026·7 points·2 comments
Visit ProjectView on HN

AI Analysis

●●●BangerSolve My ProblemShip It

MCP testing without test code—records, generates mocks, catches Tool Poisoning, gates CI.

Strengths
  • •Deterministic, reproducible testing with zero LLM flakiness—records sessions and replays them to catch regressions.
  • •Security audits catch real vulnerabilities (Tool Poisoning, Excessive Agency) before production, addressing a category gap.
  • •One command generates working GitHub Actions / GitLab CI configs—zero friction to integrate into pipelines.
Weaknesses
  • •MCP is young; adoption depends on Anthropic/Claude ecosystem growth—narrow TAM right now.
  • •Feature list is broad (13 CLI commands, 8 rules, 5 reporters, web dashboard) but unclear which genuinely differentiate vs. standard test harness patterns.
Target Audience

MCP server developers, AI application builders, DevOps engineers

Similar To

MCP Inspector · pytest · Vitest

Post Description

Hi HN,

I've been building MCPSpec, an open-source CLI for MCP server reliability. Record sessions, generate mock servers, catch Tool Poisoning, and fail your CI build when something's wrong — without writing test code.

There are ways to validate MCP servers today — the MCP Inspector, ad-hoc SDK scripts, unit tests for server internals — but nothing that handles regression detection, security auditing, mock generation, and CI pass/fail checks in one tool. MCPSpec does that:

1. Record a session against your real server, replay it after changes to catch regressions

2. Generate a standalone .js mock from any recording — no API keys, no live server needed in CI

3. Security audit with 8 rules including Tool Poisoning (prompt injection hidden in tool descriptions)

4. 0-100 quality score across documentation, schema quality, error handling, responsiveness, and security

5. One command to generate GitHub Actions / GitLab CI configs

No LLMs in the loop. Deterministic and fast. Ships with 70 ready-to-run tests for 7 popular MCP servers.

GitHub: https://github.com/light-handle/mcpspec Docs: https://light-handle.github.io/mcpspec/

Would love feedback or feature ideas.

Similar Projects

Developer Tools●Mid

How we made MCP development feel good

Testing harness for MCP servers solves refresh pain alongside Smithery and official SDKs.

Ship ItSolve My Problem
pzullo
611mo ago