uv-run

Runs a command in a uv-managed environment and returns structured output.

SERVERBuild SOURCEDave-London/Pare

High RISK CLASS

Category Execute

Parameters 00 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-build/uv-run.md

WHAT IT DOES

What uv-run does on Build

AI agents invoke uv-run to trigger actions in Build. 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.

RISK

Why uv-run is rated High

This tool executes external commands (via uv, a Python package manager and runner) in a managed environment. The blast radius is high because an AI agent could execute harmful commands (system operations, data exfiltration, lateral movement) if given malicious or misguided instructions. While the output is structured as JSON diagnostics, the action itself is execution of arbitrary code.

From the tool's definition Tool description states 'Runs a command in a uv-managed environment' — directly executes arbitrary commands with effects dependent on the command argument provided.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs uv-run safely

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

uv-run Rate-limited

uv-run 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": {
    "uv-run": {
      "limits": [
        {
          "counter": "uv-run_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 Build, apply this rule, and every uv-run call is checked against it from then on.

FAQ

Questions about uv-run

What does the uv-run tool do? +

Runs a command in a uv-managed environment and returns structured output. It is categorised as a Execute tool in the Build MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on uv-run? +

Register the Build MCP server in PolicyLayer and add a rule for uv-run: 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 Build. Nothing to install.

What risk level is uv-run? +

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

Can I rate-limit uv-run? +

Yes. Add a rate_limit block to the uv-run 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 uv-run completely? +

Set action: deny in the PolicyLayer policy for uv-run. 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 uv-run? +

uv-run is provided by the Build 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

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