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·3 min read·Shashank Bindal

Quelltest Is Now Agent-Native: A Local MCP Server Ships in the Package

pip install quelltest[mcp] and Claude Code, Cursor, or any MCP client can find untested edge cases and write Gate-5-proven tests directly — no terminal, no cloud, nothing leaves your machine.

Quelltest Is Now Agent-Native

Starting today, Quelltest ships a local MCP server inside the pip package. Two steps and your coding agent can operate it directly:

pip install "quelltest[mcp]"
// .mcp.json in your project root
{ "mcpServers": { "quelltest": { "command": "quelltest-mcp" } } }

That's the whole setup. Now ask Claude Code to "find untested edge cases in this project and fix the payment ones" — and it does, in-session, without you touching a terminal.

Why I changed direction

The first version of our Claude integration was a cloud connector: sync your readiness reports up, and Claude.ai could answer questions about your PRS trend. It worked. It also missed the point.

Reading a score in a chat window makes Claude a spectator. What I actually wanted — what I kept doing manually all day — was Claude as an operator: write a function, immediately check what's untested, write the proven test, move on. The loop belongs inside the coding session, next to the code, not in a dashboard.

MCP made the right version almost embarrassingly simple. The server is a thin stdio wrapper over the same SDK the CLI uses. There is no cloud component. There is no network call. The agent spawns a process, the process reads your working tree, results go back over stdio, done.

The five tools

ToolWhat the agent gets
find_edge_casesDocumented requirements with no test — with file:line locations
write_verified_testsA pytest test per gap, each proven through all 5 gates, written to disk
get_prs_scoreProduction Readiness Score with tier and per-file breakdown
prove_fileCoverage ratio for one file or one function
reproduce_bugA natural-language bug description turned into a verified failing test

The important part isn't the tool list — it's what the tools refuse to do. write_verified_tests will not write a test that didn't pass Gate 5, where we inject the violation into your source and require the test to fail. An agent calling this tool cannot flood your repo with decorative tests. The pipeline physically won't let it.

That matters more in the agent era, not less. Agents generate tests at 50x human speed, and unverified tests at 50x speed is 50x more false confidence. Verification is the part that has to stay ruthless.

There's a Claude Code plugin too

If you live in Claude Code, the plugin bundles a skill that teaches Claude the workflows — scan after editing, score before a PR, reproduce bugs as failing tests:

/plugin marketplace add quelltest/quelltest-lib
/plugin install quelltest@quelltest

Then /quelltest find src/, /quelltest score, or plain English.

What about the cloud connector?

Still there, still useful for the team-dashboard case — PRS trends across projects, readiness questions in Claude.ai chat. But it's now the optional add-on, not the story. The story runs on your machine.

Full setup docs: quelltest.com/docs/mcp. If you hit a rough edge, open an issue — this is a fresh surface and I want the bug reports.

Try Quell

Install Quell and run it on your codebase — no API key, no configuration required.