How is a semantic diff different from a normal file diff?

A normal diff shows text changes; a semantic diff understands the protocol logic. It can tell you if a field became required or if a capability was deprecated, even if the file structure changed.

What are the three verification approaches used?

It uses Narya Types for syntax, GF(3) Evaluators for coordination logic, and Unison Effects for algebraic action traces. All three must agree for a result to be considered valid.

Can this help me fix broken MCP integrations?

Yes, it generates minimal counterexamples that show exactly why a message failed a specific spec version and provides a suggested fix for the payload.

What is the MCP Spec Checker skill?

It is a specialized tool for Claude Code that performs deep semantic analysis of Model Context Protocol specifications to ensure implementations are compliant and identify breaking changes.

Which MCP versions are supported?

The skill currently focuses on the transition and differences between the 0618 (June 2024) and 1125 (November 2025) Model Context Protocol specifications.

MCP Spec Checker

Name: MCP Spec Checker
Author: plurigrid

byplurigrid

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Seguridad y Pruebas

Performs semantic diffing and triadic verification on Model Context Protocol (MCP) specifications to detect breaking changes and validate compliance.

The MCP Spec Checker is a sophisticated protocol verification engine designed to manage the evolution of Model Context Protocol (MCP) specifications. It goes beyond simple text diffing by using a triadic verification approach—combining Narya bidirectional types, GF(3) predicate evaluators, and Unison-style algebraic effects—to ensure semantic consistency. This skill is essential for developers migrating between spec versions (such as 0618 and 1125), as it identifies breaking changes, generates minimal counterexamples for debugging, and provides a cross-validated consensus on message validity.

Características Principales

018 GitHub stars

02Triadic cross-validation using types, evaluators, and algebraic effects

03Automatic generation of minimal counterexamples for protocol failures

04Comprehensive trace validation for multi-step protocol interactions

05Bidirectional type checking (chk/syn/nosyn) for JSON-RPC messages

06Predicate-level semantic diffing between MCP versions 0618 and 1125

Casos de Uso

01Identifying exactly where custom protocol implementations deviate from the spec

02Validating complex protocol message traces against formal invariants

03Migrating MCP-compliant servers and clients to the latest protocol version

What are Skills?·How to Install

Install with 🐟 Skill.Fish

npx skillfish add plurigrid/asi mcp-spec-checker

For use in Claude.ai and ChatGPT

Download Skill