pytest

Runs pytest and returns structured test results (passed, failed, errors, skipped, failures).

SERVERPython SOURCEDave-London/Pare

High RISK CLASS

Category Execute

Parameters 120 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/io-github-dave-london-pare-python/pytest.md

WHAT IT DOES

What pytest does on Python

AI agents invoke pytest to trigger actions in Python. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call: builds kicked off, notifications sent, workflows started.

Parameter	Type	Required	Description
`env`	object	—	Additional environment variables for the pytest process, merged over the parent environment (e.g. {"PYTHONPATH": "src"} for src-layout projects)
`path`	string	—	Project root path
`compact`	boolean	—	Prefer compact output
`keyword`	string	—	Keyword expression for test filtering (-k EXPR)
`markers`	string	—	Pytest marker expression (e.g. "not slow")
`maxFail`	integer	—	Stop after N failures (--maxfail=N)
`targets`	array	—	Test files or directories to run (default: auto-discover)
`verbose`	boolean	—	Enable verbose output
`coverage`	string	—	Source directory for coverage measurement (--cov=SOURCE)
`parallel`	integer	—	Number of parallel workers for pytest-xdist (-n NUM, 0=auto)
`exitFirst`	boolean	—	Stop on first failure (-x)
`extraArgs`	array	—	Additional pytest CLI arguments passed through verbatim (e.g. ["-p", "no:logfire"] to disable a broken plugin). Each element is validated for control characters

Parameters from the server's own tool schema.

RISK

Why pytest is rated High

Running pytest executes arbitrary Python code contained in test files. A malicious or misconfigured test suite could perform destructive operations, exfiltrate data, or cause side effects. The tool actively runs code rather than just reading or writing data, placing it firmly in Execute. Severity is high because the blast radius depends entirely on what the executed tests do, and there is no sandboxing implied.

From the tool's definition "Runs pytest" — executes the pytest test runner, which runs arbitrary Python test code

Risk signalsAccepts file system path (path) · High parameter count (18 properties)

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs pytest safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Python, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For pytest, this is the rule to start with:

pytest Rate-limited

pytest stays usable, but rate-capped: a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "pytest": {
      "limits": [
        {
          "counter": "pytest_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Python, apply this rule, and every pytest call is checked against it from then on.

FAQ

Questions about pytest

What does the pytest tool do? +

Runs pytest and returns structured test results (passed, failed, errors, skipped, failures). It is categorised as a Execute tool in the Python MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

What parameters does pytest accept? +

pytest accepts 12 parameters: env, path, compact, keyword, markers, maxFail, targets, verbose, coverage, parallel, exitFirst, extraArgs. The full parameter table on this page comes from the server's own tool schema.

How do I enforce a policy on pytest? +

Register the Python MCP server in PolicyLayer and add a rule for pytest: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Python. Nothing to install.

What risk level is pytest? +

pytest is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit pytest? +

Yes. Add a rate_limit block to the pytest rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.

How do I block pytest completely? +

Set action: deny in the PolicyLayer policy for pytest. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.

What MCP server provides pytest? +

pytest is provided by the Python MCP server (Dave-London/Pare). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

KEEP EXPLORING

More on Python, and thousands of servers like it.

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Across the catalogue

All high-risk MCP tools → The MCP Attack Database →

Guides

Govern code and CI agents →Agent sandbox →Least privilege for MCP →