MCP Contract

A project structure for Claude extensions that have outgrown a single file.

v0.1.0-draft Apache-2.0 JSON Schema draft 2020-12

MCP Prompts    = source code (operational reasoning, portable)
MCP Tools      = runtime libraries (state + execution, portable)
MCP Apps       = UI framework (interactive views, portable)
Platform skill = compiler flags (thin per-platform wrapper)
Claude/ChatGPT = the compiler

Prompts ──provides──> ["analysis-request"]
                            |
Tools   ──provides──> ["sec-filings", "comps-table"]
                            |
Apps    ──consumes──> ["comps-table", "analysis-request"]

Skills  ──targets───> ["claude", "gpt"]

Compiler (Claude, GPT, Gemini, Llama) links it all at runtime.

Prompts

Reasoning logic. What to think about and what output shape to produce.

analogous to source code

Tools

Runtime execution. APIs, databases, computation engines with typed schemas.

analogous to runtime libraries

Apps

Interactive views. Dashboards, reports, forms that consume contract schemas.

analogous to UI frameworks

Skills

Platform adaptation. Thin wrappers for Claude, GPT, Cursor, etc.

analogous to compiler flags

Get Started

# Install the CLI pip install mcpc-cli # Scaffold a new bundle mcpc init my-workflow # Validate contracts mcpc validate # Pack for distribution mcpc pack

Why?

A small Claude extension is a single prompt file. Anything useful grows past that — a tool server, a UI, schemas, platform hints. Past a certain size, the layers start bleeding into each other: prompts name tools directly, tool servers grow reasoning, UIs render fields schemas no longer have, platform adaptation scatters.

MCP Contract is the layout that stops the drift. Four layers with explicit boundaries, a manifest that declares what each layer publishes and consumes, and a CLI that validates it. No custom schema language. No new runtime. Think create-react-app for Claude extensions.

Typed contracts also permit cross-bundle composition downstream — but that's a consequence of the structure, not the reason to adopt it today.

Reference Implementation

Synth Ops is an intelligent infrastructure operations system built as an MCP Contract bundle.

Schema

The manifest schema is hosted at mcpcontracts.com/schema/0.1.0.json for editor validation.