ltspice-mcp

ltspice-mcp is an MCP server that lets an AI assistant simulate circuits with LTspice or ngspice and edit LTspice schematics. Its stated goals are speed, correctness, token efficiency, and clean schematics. The assistant uses ready-made, well-tested tools that know the quirks of SPICE and of each simulator, instead of improvised scripts. Mechanical checks catch common errors before a file is written or run, and results come back as named numbers, such as a phase margin, instead of waveforms to read.

Sweeps, corners, and Monte Carlo take one call and run as background jobs that survive a restart and can be replayed. With LTspice 26.1 or later on Windows, the user and the assistant can edit the same open schematic. Everything the tools do is also available from Python as the ltspice_mcp.api package, and the server is built on spicelib. The README states it is a work in progress and to expect breaking changes across versions.

It installs with uv tool install or pipx, and works with Claude Code (through a plugin marketplace), Claude Desktop (through a built extension), and other MCP clients. The server needs Python 3.11 or newer plus LTspice or ngspice on the same machine. Editing .asc schematics needs LTspice, because the server uses LTspice symbol libraries. macOS is not supported yet: the server cannot read simulation results there.