add_library_symbol_property

Add or update a custom property (Manufacturer, MPN, LCSC, etc.) on a symbol definition in the lib_symbols section. This makes the property available to all instances of that symbol in the schematic.

SERVERKiCAD-MCP-Server SOURCEmixelpixx/kicad-mcp-server

Medium RISK CLASS

Category Write

Parameters 00 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/mixelpixx-kicad-mcp-server/add-library-symbol-property.md

WHAT IT DOES

What add_library_symbol_property does on KiCAD-MCP-Server

AI agents use add_library_symbol_property to create or update resources in KiCAD-MCP-Server, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your KiCAD-MCP-Server environment.

RISK

Why add_library_symbol_property is rated Medium

This tool creates or modifies metadata (properties like Manufacturer, MPN, LCSC) on symbol definitions. It is reversible—properties can be updated or removed—and does not delete data or execute arbitrary code. The modification affects the schematic library definitions, making it a Write operation.

From the tool's definition Tool description states it will "Add or update a custom property" on a symbol definition, which modifies the lib_symbols section and affects all instances of that symbol in the schematic.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs add_library_symbol_property safely

PolicyLayer is an MCP gateway: it sits between your AI agents and KiCAD-MCP-Server, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For add_library_symbol_property, this is the rule to start with:

add_library_symbol_property Rate-limited

add_library_symbol_property 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": {
    "add_library_symbol_property": {
      "limits": [
        {
          "counter": "add_library_symbol_property_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect KiCAD-MCP-Server, apply this rule, and every add_library_symbol_property call is checked against it from then on.

FAQ

Questions about add_library_symbol_property

What does the add_library_symbol_property tool do? +

Add or update a custom property (Manufacturer, MPN, LCSC, etc.) on a symbol definition in the lib_symbols section. This makes the property available to all instances of that symbol in the schematic. It is categorised as a Write tool in the KiCAD-MCP-Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on add_library_symbol_property? +

Register the KiCAD-MCP-Server MCP server in PolicyLayer and add a rule for add_library_symbol_property: 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 add_library_symbol_property? +

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

Can I rate-limit add_library_symbol_property? +

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

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

add_library_symbol_property 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.

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