PREFERRED tool for pad-to-pad routing. Looks up pad positions automatically, detects the net from the pad, and — critically — if the two pads are on different copper layers (e.g. J1 on F.Cu and J2 on B.Cu) automatically inserts a via at the midpoint so the connection is complete. Always use this ...
AI agents use route_pad_to_pad 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.
This tool creates or modifies traces and vias in a KiCAD PCB design, which are typical Write operations (reversible changes to design data). While it modifies circuit connectivity, it does not irreversibly delete data (Destructive), execute arbitrary code (Execute), or move money (Financial). The recommendation to 'always use this instead of route_trace' indicates it is a primary design modification tool.
From the tool's definition Tool description states it performs pad-to-pad routing, automatically inserts vias, and creates connections in a PCB design—these are reversible modifications to the circuit layout.
Documented attack patterns abuse exactly the kind of access route_pad_to_pad gives an agent:
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 route_pad_to_pad:
{
"version": "1",
"default": "deny",
"tools": {
"route_pad_to_pad": {
"limits": [
{
"counter": "route_pad_to_pad_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}route_pad_to_pad 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.
Free to start. No card required.
PREFERRED tool for pad-to-pad routing. Looks up pad positions automatically, detects the net from the pad, and — critically — if the two pads are on different copper layers (e.g. J1 on F.Cu and J2 on B.Cu) automatically inserts a via at the midpoint so the connection is complete. Always use this instead of route_trace when routing between named component pads. 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.
Register the KiCAD-MCP-Server MCP server in PolicyLayer and add a rule for route_pad_to_pad: 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.
route_pad_to_pad is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the route_pad_to_pad 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 route_pad_to_pad. 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.
route_pad_to_pad 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.
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.
Free to start. No card required.
157 KiCAD-MCP-Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.