AI agents call get_crate_versions to retrieve information from Rust Docs MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves version metadata from a public documentation repository (docs.rs). It has no side effects—it does not modify, delete, execute code, or incur financial obligations. The absence of a detailed description is mitigated by the clear pattern of read-only tools in the server's capability list and the transparent nature of documentation queries.
From the tool's definition Tool name 'get_crate_versions' indicates retrieval of version information for crates from Rust documentation.
Documented attack patterns abuse exactly the kind of access get_crate_versions gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Rust Docs MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for get_crate_versions:
{
"version": "1",
"default": "deny",
"tools": {
"get_crate_versions": {}
}
}get_crate_versions is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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get_crate_versions. It is categorised as a Read tool in the Rust Docs MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Rust Docs MCP Server MCP server in PolicyLayer and add a rule for get_crate_versions: 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 Rust Docs MCP Server. Nothing to install.
get_crate_versions is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the get_crate_versions 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 get_crate_versions. 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.
get_crate_versions is provided by the Rust Docs MCP Server MCP server (laptou/rust-docs-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Rust Docs MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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7 Rust Docs MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.