Runs a command in a uv-managed environment and returns structured output.
AI agents invoke uv-run to trigger actions in Http. 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.
This tool executes arbitrary commands in a controlled environment. While the environment is managed by uv (providing some isolation), it still permits running any command whose effects depend on the arguments passed. This represents Execute rather than Read (has side effects), Write (effects may be destructive), or Destructive (depends on the command run).
From the tool's definition Tool name 'uv-run' and description 'Runs a command in a uv-managed environment' indicates arbitrary command execution. The uv tool is a Python package manager that can execute scripts and commands within isolated environments.
Documented attack patterns abuse exactly the kind of access uv-run gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Http, and nothing reaches the server without passing your rules. This is the rule we recommend for uv-run:
{
"version": "1",
"default": "deny",
"tools": {
"uv-run": {
"limits": [
{
"counter": "uv-run_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}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.
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Runs a command in a uv-managed environment and returns structured output. It is categorised as a Execute tool in the Http MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Http 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 Http. Nothing to install.
uv-run is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
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.
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.
uv-run is provided by the Http MCP server (@paretools/http). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Http, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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