FERS MCP server, local

Structural finite-element analysis for AI agents, solving on your own machine. The same tools as the hosted FERS MCP server: build beams, frames, trusses and plates, add loads and EN 1990 combinations, run modal, buckling and seismic analyses and Eurocode unity checks. The difference is where the solve runs: here, with the FERS engine (Rust compiled to WebAssembly) inside this process, not on a server.

• Results come back in seconds and stay on your machine.
• No per-solve charges, no request timeouts, no upload size limit.
• Free for non-commercial use, models up to 100 members. Commercial use needs a FERS Pro API key, which also raises the limit to 10,000 members.

Install

Node.js 18 or newer. The package runs with npx, nothing else to install.

Claude Desktop. Download fers-mcp.mcpb from the latest release and double-click it, or add this to claude_desktop_config.json (Settings, Developer, Edit Config):

{
  "mcpServers": {
    "fers": {
      "command": "npx",
      "args": ["-y", "@ferscloud/fers-mcp"],
      "env": { "FERS_API_KEY": "<your key, optional>" }
    }
  }
}

Claude Code

claude mcp add --transport stdio fers --env FERS_API_KEY=<your key> -- npx -y @ferscloud/fers-mcp

Cursor (.cursor/mcp.json) and most other clients use the same shape as Claude Desktop, with "type": "stdio". VS Code (.vscode/mcp.json) uses a top-level servers key instead of mcpServers. Codex CLI (~/.codex/config.toml):

[mcp_servers.fers]
command = "npx"
args = ["-y", "@ferscloud/fers-mcp"]
env = { FERS_API_KEY = "<your key>" }

ChatGPT desktop: Settings, MCP servers, Add server, STDIO, command npx -y @ferscloud/fers-mcp.

Clients that cannot start a program on your computer (Claude and ChatGPT in the browser or on a phone) can use the hosted server at https://ferscloud.com/api/mcp instead. It authors and validates models there and hands back a link that solves the model in your browser.

Options

get_usage reports the tier in force, why, and the engine version.

What leaves your machine

Your models never do. With FERS_API_KEY set, the server sends that key to FersCloud to obtain a 30-minute solve token; the engine verifies the token offline. Without a key nothing is sent at all and every solve runs on the Free tier.

Licence

PolyForm Strict License 1.0.0, see LICENSE: free for any non-commercial purpose. Commercial use needs a paid FERS Cloud plan (https://ferscloud.com/pricing), which includes the commercial licence. The licence does not allow modifying or redistributing the package. Documentation: https://ferscloud.com/mcp

Releasing (maintainers)

The package is built from the FERS Cloud sources (src/lib/mcp-core, src/mcp-local) by npm run build:mcp-local, and released by the GitHub workflow publish-mcp.yml, which tests, packs, installs and smoke-tests both the npm package and the Claude Desktop bundle before it publishes anything.

• The version follows the engine the package bundles: <engine minor>.<engine patch>.<n>, so engine 0.2.75 gives 2.75.0 and another release on that engine 2.75.1. After an engine bump run node scripts/set-mcp-version.mjs; for a server-only change, node scripts/set-mcp-version.mjs --next. It writes mcp-local/package.json, mcp-local/manifest.json, server.json, public/.well-known/mcp/server-card.json and SERVER_VERSION in src/lib/mcp-core/server.ts; mcpManifests.test.ts fails until they agree and follow the engine pin.
• Releases publish themselves. After every successful prod deploy the workflow releases the version when npm does not have it yet: npm, the mcp-v<version> release with the .mcpb on FERS_core, and the official registry. A manual run builds and verifies; with publish = true it also finishes a release whose later step failed, since each publish step skips what already exists.
• The first release (2.1.0) was published by hand, because npm attaches a trusted publisher only to an existing package. The trusted publisher is Jeroen124/FERS_cloud, workflow publish-mcp.yml.