# Codex Multisim Mcp

> Let OpenAI Codex control NI Multisim through a local MCP server for component placement, wiring, screenshots, and saving designs.

- **Type:** MCP server
- **Install:** `agentstack add mcp-fenxin-fx-codex-multisim-mcp`
- **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior
- **Seller:** [fenxin-fx](https://agentstack.voostack.com/s/fenxin-fx)
- **Installs:** 0
- **Category:** [AI & ML](https://agentstack.voostack.com/c/ai-and-ml)
- **Latest version:** 0.1.0
- **License:** MIT
- **Upstream author:** [fenxin-fx](https://github.com/fenxin-fx)
- **Source:** https://github.com/fenxin-fx/codex-multisim-mcp

## Install

```sh
agentstack add mcp-fenxin-fx-codex-multisim-mcp
```

Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent.

## About

# Codex Multisim MCP

Control NI Multisim from OpenAI Codex through a local Model Context Protocol
(MCP) server. Codex can launch Multisim, place components, draw wires, save a
design, and capture the Multisim window for visual verification.

The server is local and dependency-light: it uses a small Win32 bridge and a
plain Node.js STDIO MCP server. No Python, AutoHotkey, npm install, cloud
service, or API key is required.

## Requirements

- Windows 10 or Windows 11
- NI Multisim installed locally
- OpenAI Codex app, CLI, or IDE extension
- Node.js 18 or newer

Multisim 14.0 in Simplified Chinese and English has been tested. Component
dialog detection also includes a language-independent structural fallback.
Other Multisim releases may need calibration through
`multisim_inspect_controls`.

## Install

1. Download `codex-multisim-mcp-windows-v1.0.0.zip` from GitHub Releases.
2. Extract the archive.
3. Open PowerShell in the extracted directory.
4. Run:

```powershell
powershell.exe -NoProfile -ExecutionPolicy Bypass -File .\install.ps1
```

The installer:

- verifies Node.js;
- copies the runtime to `%LOCALAPPDATA%\MultisimMCP`;
- adds a managed `multisim` block to `~/.codex/config.toml`;
- runs an MCP protocol smoke test.

Restart Codex or open a new Codex thread after installation. Then try:

> Check Multisim status, open it, and place a 74LS00 on a new design.

### Project-only install

To expose the MCP only inside one trusted Codex project:

```powershell
powershell.exe -NoProfile -ExecutionPolicy Bypass -File .\install.ps1 `
  -Scope Project `
  -ProjectPath "C:\path\to\your\project"
```

This installs the runtime under the project's `.codex\tools` directory and
updates that project's `.codex\config.toml`.

### Custom Multisim location

The bridge searches the Windows file associations and standard National
Instruments installation directories. If discovery fails, set:

```powershell
$env:MULTISIM_EXE = "D:\NI\Circuit Design Suite\multisim.exe"
```

For a persistent user environment variable:

```powershell
[Environment]::SetEnvironmentVariable(
  "MULTISIM_EXE",
  "D:\NI\Circuit Design Suite\multisim.exe",
  "User"
)
```

Restart Codex after changing the persistent variable.

## Available tools

| Tool | Purpose |
| --- | --- |
| `multisim_status` | Detect Multisim and report its active window |
| `multisim_launch` | Start Multisim or open a design |
| `multisim_new_design` | Create a blank design |
| `multisim_place_component` | Search and place a database component |
| `multisim_wire` | Draw a wire through optional explicit via points |
| `multisim_auto_route` | Draw a one-bend Manhattan route |
| `multisim_save_design` | Save or Save As |
| `multisim_screenshot` | Capture the Multisim window |
| `multisim_inspect_controls` | Inspect controls for version calibration |

## Coordinate model

Placement and wiring coordinates are physical pixels relative to the top-left
corner of the Multisim main window. A reliable Codex workflow is:

1. call `multisim_status`;
2. call `multisim_screenshot`;
3. place components;
4. capture another screenshot;
5. wire the visible pin endpoints;
6. verify and save.

`multisim_auto_route` is deterministic one-bend routing, not a full PCB or
schematic obstacle-solving router. Use explicit `via` points with
`multisim_wire` for multi-bend routes.

## Uninstall

```powershell
powershell.exe -NoProfile -ExecutionPolicy Bypass -File .\uninstall.ps1
```

For a project-only installation:

```powershell
powershell.exe -NoProfile -ExecutionPolicy Bypass -File .\uninstall.ps1 `
  -Scope Project `
  -ProjectPath "C:\path\to\your\project"
```

The uninstaller removes only the marked configuration block managed by this
project. Other Codex settings and MCP servers are left untouched.

## Build from source

The release archive and repository include `bin\multisim-cli.exe`. To rebuild
it using the .NET Framework compiler included with Windows:

```powershell
powershell.exe -NoProfile -ExecutionPolicy Bypass -File .\build.ps1
node .\test\protocol-smoke.js
```

Create a GitHub-ready release archive:

```powershell
powershell.exe -NoProfile -ExecutionPolicy Bypass `
  -File .\scripts\package-release.ps1
```

## Security notes

This MCP controls a desktop application with simulated keyboard and mouse
input. Codex is configured to prompt before state-changing Multisim tools.
Review requested actions before approval, especially Save As paths.

## License

MIT

## Source & license

This open-source MCP server is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [fenxin-fx](https://github.com/fenxin-fx)
- **Source:** [fenxin-fx/codex-multisim-mcp](https://github.com/fenxin-fx/codex-multisim-mcp)
- **License:** MIT

Install and usage instructions live in the source repository linked above.

## Pricing

- **Free** — Free

## Security capabilities

Automated source analysis of v0.1.0 — what this tool can access:

- **Network access:** no
- **Filesystem access:** no
- **Shell / process execution:** no
- **Environment & secrets:** no
- **Dynamic code execution:** no

*"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.*


## Versions

- **0.1.0** — security scan: passed — Imported from the upstream source.

## Links

- Listing page: https://agentstack.voostack.com/l/mcp-fenxin-fx-codex-multisim-mcp
- Seller: https://agentstack.voostack.com/s/fenxin-fx
- Browse the marketplace: https://agentstack.voostack.com/browse

---
Listed on AgentStack — the marketplace for AI agent skills and MCP servers. Every listing is security-reviewed. Creators keep 70%.