uv-run
Runs a command in a uv-managed environment and returns structured output.
This record as markdown: /tools/io-github-dave-london-cargo/uv-run.md
What uv-run does on Cargo
AI agents invoke uv-run to trigger actions in Cargo. 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.
Why uv-run is rated High
This tool executes arbitrary commands in a uv-managed Python environment. While the blast radius depends on the environment's permissions and what commands are invoked, the tool fundamentally enables code execution outside the sandbox with effects that cannot be predicted statically. Misuse could lead to system compromise, data exfiltration, or resource exhaustion.
From the tool's definition Tool name 'uv-run' with description 'Runs a command in a uv-managed environment' indicates arbitrary command execution. The description explicitly states it 'runs a command', which permits execution of external operations whose effects depend on arguments.
Attacks that exploit this kind of access
The rule that runs uv-run safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Cargo, 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 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.
The button opens the PolicyLayer dashboard: create your workspace, connect Cargo, apply this rule, and every uv-run call is checked against it from then on.
Questions about uv-run
Runs a command in a uv-managed environment and returns structured output. It is categorised as a Execute tool in the Cargo MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Cargo 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 Cargo. 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 Cargo MCP server (Dave-London/Pare). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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