@casys/mcp-tolerance

Deterministic ISO 286-1:2010 size-tolerance calculations and linear 1D stack-ups, available as an MCP server and a Deno library.

Give it H7/g6 at 25 mm and it reports the actual dimensional relationship:

Member	Limits
Hole H7	25.000–25.021 mm
Shaft g6	24.980–24.993 mm
Clearance	0.007–0.041 mm

It calculates; it does not inspect a part, choose a fit for an application, or declare a design conformant.

_{Fixture preview generated through the real bundled viewer and exact tool result. It is a demo surface, not a recorded Digital Thread result or a verdict.}

Start it

Desktop / stdio

deno run \
  --allow-env \
  --allow-read=mcp-server.yaml \
  --allow-net=jsr.io \
  jsr:@casys/mcp-tolerance@0.3.5/server \
  --stdio

Minimal MCP client configuration:

{
  "mcpServers": {
    "tolerance": {
      "command": "deno",
      "args": [
        "run",
        "--allow-env",
        "--allow-read=mcp-server.yaml",
        "--allow-net=jsr.io",
        "jsr:@casys/mcp-tolerance@0.3.5/server",
        "--stdio"
      ]
    }
  }
}

Stateless HTTP

deno run \
  --allow-env \
  --allow-read=mcp-server.yaml \
  --allow-net=127.0.0.1:3019,jsr.io \
  jsr:@casys/mcp-tolerance@0.3.5/server \
  --port=3019

The endpoint is http://127.0.0.1:3019/mcp and speaks the stateless MCP 2026-07-28 contract.

Container

docker run --rm -p 127.0.0.1:3019:3019 \
  ghcr.io/casys-ai/mcp-tolerance:0.3.5 http

Use stdio instead of http for an interactive container client. Version tags and latest are convenient selectors; pin the published OCI digest when the deployment itself must be reproducible.

What it covers

• IT grades and supported hole/shaft limit classes over (0, 500] mm.
• Hole-basis and general hole/shaft fit analysis with signed clearance ranges.
• Scalar 1D chains with worst-case and RSS intervals plus reconstructable contributor terms.

Every result carries provenance, explicit not_checked limits, and no invented pass/fail verdict. The complete class coverage, sign conventions, formulas, stack-up assumptions, and exclusions live in the technical reference.

MCP Apps

MCP Apps-capable hosts receive compact provider-owned surfaces for limits, fits, and stack-ups. Text-only hosts keep the same content and structuredContent.

The package exports @casys/mcp-tolerance/view-app-manifest, which declares the whole-view resources and their read-only viewer.session.apply contracts. A recording host may replay an exact projection; this provider does not create a Digital Thread session, anchor, approval, or manufacturing claim.

Library

deno add jsr:@casys/mcp-tolerance@0.3.5

import { computeFit, fundamentalTolerance } from "@casys/mcp-tolerance";

console.log(fundamentalTolerance(7, 25)); // 21 µm
console.log(computeFit("H7", "g6", 25).fit); // clearance, 7–41 µm

Documentation

• Technical reference — contracts, classes, formulas, signs, stack-ups, boundaries, and verification.
• Running and contributing — transports, containers, viewer builds, release gates, and deployment safety.
• Security policy · Changelog · Citation

For a checkout, the short validation path is:

deno task test
deno task release:check

MIT licensed. This project references ISO 286-1:2010 but is not an official ISO publication or certification service.