list_library_symbols

THE RISK

Low Risk

Why list_library_symbols needs a policy

This tool queries and returns data about symbols in a KiCAD library without creating, modifying, deleting, or executing any operations. It is a pure read operation with minimal blast radius—misuse would only expose library contents, not cause damage to the design or system.

From the tool's definition Tool name 'list_library_symbols' and description 'List all symbols in a specific KiCAD symbol library' indicate a retrieval operation with no modification or side effects.

Documented attack patterns abuse exactly the kind of access list_library_symbols gives an agent:

POLICY

How to control list_library_symbols

PolicyLayer is an MCP gateway — it sits between your AI agents and KiCAD-MCP-Server, and nothing reaches the server without passing your rules. This is the rule we recommend for list_library_symbols:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "list_library_symbols": {}
  }
}

list_library_symbols is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.

Create a free account and register KiCAD-MCP-Server — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

CAP THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More KiCAD-MCP-Server tools

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Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Data exfiltration → How read access becomes an exfiltration channel when chained with untrusted content.
MCP token cost → What connecting this server costs in context-window tokens on every request.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about list_library_symbols

What does the list_library_symbols tool do? +

List all symbols in a specific KiCAD symbol library (global or project-scope when projectPath is supplied or a project has been opened). It is categorised as a Read tool in the KiCAD-MCP-Server MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on list_library_symbols? +

Register the KiCAD-MCP-Server MCP server in PolicyLayer and add a rule for list_library_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 KiCAD-MCP-Server. Nothing to install.

What risk level is list_library_symbols? +

list_library_symbols is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit list_library_symbols? +

Yes. Add a rate_limit block to the list_library_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.

How do I block list_library_symbols completely? +

Set action: deny in the PolicyLayer policy for list_library_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.

What MCP server provides list_library_symbols? +

list_library_symbols is provided by the KiCAD-MCP-Server MCP server (mixelpixx/kicad-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every KiCAD-MCP-Server tool call.

Start from KiCAD-MCP-Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →