List all symbols in a crate. Use when implementing traits or exploring available types. Shows structs, enums, traits with their paths.
AI agents call list_symbols to retrieve information from Cargo Doc 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 and queries documentation metadata (symbols, types, paths) without side effects. It does not execute code, modify data, or trigger external operations. This is a straightforward Read operation used for exploration and discovery of available Rust types in documentation.
From the tool's definition Tool description states it 'List all symbols in a crate' and 'Shows structs, enums, traits with their paths' — purely informational retrieval with no modification or execution capability.
Documented attack patterns abuse exactly the kind of access list_symbols gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Cargo Doc MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for list_symbols:
{
"version": "1",
"default": "deny",
"tools": {
"list_symbols": {}
}
}list_symbols is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
Free to start. No card required.
List all symbols in a crate. Use when implementing traits or exploring available types. Shows structs, enums, traits with their paths. It is categorised as a Read tool in the Cargo Doc MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Cargo Doc MCP Server MCP server in PolicyLayer and add a rule for list_symbols: 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 Doc MCP Server. Nothing to install.
list_symbols 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 list_symbols 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 list_symbols. 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.
list_symbols is provided by the Cargo Doc MCP Server MCP server (spacemeowx2/cargo-doc-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Cargo Doc MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
3 Cargo Doc MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.