MeshMend

Check and repair 3D-printing meshes (STL and 3MF) from an AI assistant that can run tools on your computer: Claude Desktop, Claude Code, Cursor, VS Code, Windsurf, Codex CLI, Gemini CLI or any other MCP client that starts local servers.

Ask “is ~/prints/bracket.stl watertight?”, “why does my slicer say this model has holes?” or “把这个 3MF 转成 STL”: the assistant reads the file on your machine, tells you exactly what is wrong (holes, flipped faces, inside-out shells, non-manifold edges, duplicate triangles), says honestly whether an automatic repair will fix it, and writes a repaired copy next to the original.

Your files never leave your computer. The server runs locally, reads and writes only the files you name, makes no network requests and has no telemetry. The original file is never overwritten. It is the same mesh code as the free in-browser tool at mesh-mend.pages.dev.

npx -y github:Keith-CY/meshmend-mcp

Status: version 0.1.0. Publishing to npm is pending; until then npx -y github:Keith-CY/meshmend-mcp (needs Node.js 18+ and git) runs the same build, and Claude Desktop users can install the one-click bundle from Releases.

Tools

Every result comes as readable text and as structured JSON (structuredContent, with an outputSchema). check_mesh is marked read-only; the other two only create new files (destructiveHint: false).

Where results go: next to the input, as <name>.repaired.stl (or <name>.stl for a conversion), then -2, -3, … rather than replacing anything. With output_path, an existing file is replaced only with overwrite: true, and the input file can never be the output.

Related MCP server: cad-mcp-server

Connect it

Claude Desktop

One click: download meshmend-mcp-0.1.0.mcpb from Releases and open it (or Settings → Extensions → Advanced settings → Install extension…). Claude Desktop runs it with its built-in Node.js.

Or by hand: Settings → Developer → Edit config and add to claude_desktop_config.json:

{
  "mcpServers": {
    "meshmend": {
      "command": "npx",
      "args": ["-y", "github:Keith-CY/meshmend-mcp"]
    }
  }
}

Claude Code

claude mcp add meshmend -- npx -y github:Keith-CY/meshmend-mcp

Cursor

~/.cursor/mcp.json (or .cursor/mcp.json in a project):

{
  "mcpServers": {
    "meshmend": { "command": "npx", "args": ["-y", "github:Keith-CY/meshmend-mcp"] }
  }
}

VS Code (GitHub Copilot)

.vscode/mcp.json:

{
  "servers": {
    "meshmend": { "type": "stdio", "command": "npx", "args": ["-y", "github:Keith-CY/meshmend-mcp"] }
  }
}

Windsurf

~/.codeium/windsurf/mcp_config.json: the same mcpServers block as Cursor.

Codex CLI

~/.codex/config.toml:

[mcp_servers.meshmend]
command = "npx"
args = ["-y", "github:Keith-CY/meshmend-mcp"]

Gemini CLI

~/.gemini/settings.json:

{ "mcpServers": { "meshmend": { "command": "npx", "args": ["-y", "github:Keith-CY/meshmend-mcp"] } } }

Any other client

Any MCP client that starts local (stdio) servers can run npx -y github:Keith-CY/meshmend-mcp, or node /path/to/meshmend-mcp/dist/meshmend-mcp.js from a checkout (the file has no dependencies). Ready-made files are in examples/clients/.

Give the assistant absolute paths (~ is expanded). Relative paths are resolved from the server’s working directory, which in desktop apps is often not your project folder.

Real files, before and after

From this repository’s tests and a local run (npm test repeats all but the bunny and the sphere):

What it fixes, and what it doesn’t

It fixes:

• duplicate faces and zero-area (degenerate) faces;

• inconsistent face winding (flipped normals) across ordinary shared edges;

• closed shells that are inside out, when they don’t overlap other shells;

• with fill_holes: true: simple flat holes (3–128 boundary vertices) whose bounding-box diagonal is within max_hole_span_mm.

It does not:

• weld nearby vertices (only exactly equal coordinates are joined), so it can’t close seams between surfaces;

• split non-manifold edges or vertices, remesh, or rebuild a solid;

• repair self-intersections, union overlapping parts, or check wall thickness, overhangs or supports;

• cap curved holes, nested openings or holes wider than the span;

• guarantee that a model prints. Open the result in your slicer.

Because some openings are intentional, hole filling is off unless asked for. check_mesh runs the repair in memory first, so its verdict says whether repair_mesh will actually help before anything is written.

Limits: 30 MiB per file and 250,000 triangles (the same as the website). 3MF: the primary build, components, transforms, production-extension part references and units; ZIP64, unsupported required extensions, mixed units across parts and G-code-only packages are refused with an explanation. Colours, materials and print settings are not carried into STL.

Privacy

MeshMend’s MCP server works only on your computer. It reads the files you or your assistant name and writes new STL files; it sends nothing anywhere, has no analytics or telemetry, and keeps no logs. Your AI assistant sees the tool results (counts, sizes, file paths and messages) like any other tool output, under that assistant’s own privacy terms.

Development

npm install
npm test            # builds dist/ and runs the core, file and end-to-end tests (needs Bun)
npm run pack:mcpb   # builds the Claude Desktop bundle into build/
node scripts/call.mjs check_mesh '{"path":"tests/fixtures/missing-patch.stl"}'

src/core/ is MeshMend’s mesh code, copied unchanged from the website so both give the same answers. dist/meshmend-mcp.js is a single bundled file (committed, so npx github: needs no build step); NOTICE lists the bundled packages and their licences.

Licence

MIT. The three trimesh test files are MIT-licensed by their authors (details).

The in-browser version, with a 3D preview and before/after comparison: mesh-mend.pages.dev.