Contract Diff Mcp

io.github.mrfentmenPublished by GitHub account mrfentmenv1.0.1Updated Oct 30, 2026

Aggregate local contract snapshot changes without exposing schema contents. Tools include...

VerifiedSTDIODesktop onlyFiles & StorageDeveloper Tools

Overview

AI-generated overview

Local MCP server that compares two JSON contract snapshots and returns a coarse structural fingerprint without exposing schema contents.

What you can do
  • Compare two local JSON contract snapshots using node counts, value type categories and deltas only
  • Get a coarse structural signal on whether a snapshot grew, shrank or changed shape
  • Keep schema names, paths, values, descriptions, examples and file paths out of the result
When to use it
Useful when you want a quick, privacy-preserving check of whether a generated API or JSON Schema snapshot changed structurally between two versions, without handing schema contents to an agent. It is a coarse regression signal, not a compatibility validator.
Requirements
Runs as a local Node.js process installed from the npm package contract-diff-mcp (install, build, then run the built entry point). Needs local JSON snapshot files under a root directory set by the CONTRACT_DIFF_ROOT environment variable. No accounts, keys or network access are declared.
Before you install
Reads local files, so point CONTRACT_DIFF_ROOT at a narrow directory; access is bounded by that root and realpath checks, with files capped at two megabytes. Results are structural only and do not prove endpoint compatibility or identify semantic additions and removals, so do not treat them as a full OpenAPI or JSON Schema compatibility check.

Installation

In SourceWeft

  1. Open Contract Diff Mcp in the dashboard and add it to a workspace.
  2. Enable the server for the chats that should use its tools.

Desktop only via STDIO. STDIO servers start a local process, so they need the SourceWeft desktop host.

Other MCP clients

Follow the launch instructions in the repository.

README

contract-diff-mcp

Contract Diff compares two local JSON contract snapshots and reports a coarse structural fingerprint. It is useful for quickly answering whether a generated API or schema snapshot became larger, smaller, or structurally different without handing schema contents to an agent. It does not prove endpoint compatibility or identify semantic additions and removals.

Tool

  • compare_contract_snapshots: compare two local JSON snapshots using node counts, value type categories, and deltas only. The result is a structural signal, not a semantic contract diff.

Safety

  • Local paths only, bounded by CONTRACT_DIFF_ROOT and realpath checks.
  • Files are capped at two megabytes and traversal is capped.
  • Never returns schema names, paths, values, descriptions, examples, versions, file paths, or raw contents.
  • This is a coarse regression signal, not a complete OpenAPI or JSON Schema compatibility validator.

Run

bash
npm installnpm run buildnode dist/index.js

Source: README.md at commit 1df8363

Tools

0
SourceWeft has not started this package in its sandbox yet, so its tools are not known.

Version history

1
  1. v1.0.1LatestSep 22, 2026

Score

40% of the applicable checks met

How complete this listing is, computed from the registry entry, the endpoint and public sources. Not a rating of the server and not a statement that it is safe or working today: reachability is a dated check, and no installs or reviews go into the score.

  • Reached in the last 30 days25 pts

    Keep the endpoint answering the MCP handshake; SourceWeft probes it every 30 days.

  • Auth declared10 pts

    Declare the credential headers in the registry entry, or keep the endpoint answering the probe so its auth can be classified.

  • Tools listed15 pts

    Answer tools/list without a credential, or ship a package that starts in a sandbox without one.

  • DescriptionRequired15 pts
  • Logo10 pts
  • Documentation15 pts
  • License10 pts

    Declare a license in the repository or the registry entry.