cargo_add_crate · Yaver MCP: Risk & Policy

WHAT IT DOES

What cargo_add_crate does on Yaver

AI agents use cargo_add_crate to create or update resources in Yaver — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Yaver environment.

PARAMETERS

Parameter	Type	Required	Description
`crate`	string	Yes
`directory`	string	—

Parameters from the server's own tool schema.

WHY IT NEEDS A POLICY

Why cargo_add_crate needs a policy

An AI agent can call cargo_add_crate faster than any human can review — one bad instruction and it creates or modifies resources in Yaver by the hundred, each call as confident as the last.

Risk signalsAccepts file system path (directory)

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

cargo_add_crate Rate-limited

cargo_add_crate stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "cargo_add_crate": {
      "limits": [
        {
          "counter": "cargo_add_crate_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Yaver, so you can run agents against it safely.

FAQ

Questions about cargo_add_crate

What does the cargo_add_crate tool do? +

Add a Rust dependency. It is categorised as a Write tool in the Yaver MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

What parameters does cargo_add_crate accept? +

cargo_add_crate accepts 2 parameters: crate, directory. Required: crate. The full parameter table on this page comes from the server's own tool schema.

How do I enforce a policy on cargo_add_crate? +

Register the Yaver MCP server in PolicyLayer and add a rule for cargo_add_crate: 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 Yaver. Nothing to install.

What risk level is cargo_add_crate? +

cargo_add_crate is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit cargo_add_crate? +

Yes. Add a rate_limit block to the cargo_add_crate 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 cargo_add_crate completely? +

Set action: deny in the PolicyLayer policy for cargo_add_crate. 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 cargo_add_crate? +

cargo_add_crate is provided by the Yaver MCP server (yaver-cli). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.