API & MCP

Everything a person can do on The Compatibility Engine, a program or AI agent can do with the same inputs and get the identical result.

HTTP API

• POST https://compatibilityengine.usefulweb.site/api/v1/calculate – run The Compatibility Engine
• GET https://compatibilityengine.usefulweb.site/api/v1/tool – inputs, output schema, examples
• OpenAPI 3.1: /openapi.json · /openapi.yaml
• Errors: application/problem+json; 422 includes per-field errors.

Every result contains

inputs (normalised, defaults applied), summary, result (validated against the published schema), units, assumptions, sources, warnings, computedAt and links.

MCP (Model Context Protocol)

• Streamable HTTP endpoint: https://compatibilityengine.usefulweb.site/mcp – protocol revisions 2026-07-28 (stateless) and 2025-11-25 / 2025-06-18 / 2025-03-26 (initialize handshake).
• Tools: compatibility_engine
• Local stdio connector: node src/mcp-stdio.ts --tool=compatibility-engine

{
  "mcpServers": {
    "compatibility-engine": { "type": "http", "url": "https://compatibilityengine.usefulweb.site/mcp" }
  }
}