This record as markdown: /tools/io-github-dave-london-cargo/add.md
What add does on Cargo
AI agents invoke add 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 add is rated High
'cargo add' modifies the Cargo.toml file (a Write action) but also triggers network/registry lookups and modifies the project dependency graph. Given the server context of structured cargo operations and the sibling tool 'add-package', this likely executes 'cargo add' which has side effects beyond simple data modification.
From the tool's definition Tool name 'add' on a server described as handling 'cargo operations (build, test, clippy)'; likely maps to 'cargo add' which adds dependencies to Cargo.toml
Attacks that exploit this kind of access
The rule that runs add 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 add, this is the rule to start with:
add 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 add call is checked against it from then on.
Questions about add
Runs. 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 add: 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.
add 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 add 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 add. 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.
add 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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