# pydanticcontract-mcp

A hosted MCP server that verifies Pydantic AI structured outputs, diffs schemas, and generates audit receipts for agent pipelines.

- MCP server · `type=mcp` · Claude Code, Codex, Cursor, GitHub Copilot, Windsurf (Devin Desktop), Cline, Zed, Gemini CLI
- Author: clauxel
- License: not stated · policy=link-only · description only; the file stays with the author
- Source: https://github.com/clauxel/pydantic-contract-mcp
- Updated: 2026-05-21
- HTML: https://affpapa.org/en/nevibecode/mcp/pydanticcontract-mcp

## What it does

This remote endpoint adds contract validation to automated pipelines. It exposes four tools: `contract_validate` for checking data structures, `schema_diff` for comparing two specifications, `repair_hint` to suggest fixes for schema errors, and `contract_receipt` to produce verifiable audit records.

The service is hosted commercially. Production requests will fail without a bearer token passed in the `Authorization` header, and your client environment needs Streamable HTTP transport support. Requests sent without authentication receive a structured JSON error payload.

## Requirements
- Remote server: `https://pydanticcontract.clauxel.com/mcp`

## Install

### Claude Code (native platform)

**Platform CLI: remote server**
```bash
claude mcp add --transport http pydanticcontract-mcp https://pydanticcontract.clauxel.com/mcp
```

### Codex

**Platform CLI: remote server**
```bash
codex mcp add pydanticcontract-mcp --url https://pydanticcontract.clauxel.com/mcp
```

### Cursor

**Config file**
File `.cursor/mcp.json`:
```json
{
    "mcpServers": {
        "pydanticcontract-mcp": {
            "url": "https://pydanticcontract.clauxel.com/mcp"
        }
    }
}
```

### GitHub Copilot

**Config file**
File `.vscode/mcp.json`:
```json
{
    "servers": {
        "pydanticcontract-mcp": {
            "type": "http",
            "url": "https://pydanticcontract.clauxel.com/mcp"
        }
    }
}
```

### Gemini CLI

**Platform CLI: remote server**
```bash
gemini mcp add -t http pydanticcontract-mcp https://pydanticcontract.clauxel.com/mcp
```

## When to use it
- validate Pydantic AI model output using `contract_validate`
- compare data schemas for differences via `schema_diff`
- generate fix recommendations for broken schemas using `repair_hint`
- produce verifiable execution receipts with `contract_receipt`

## Example prompts
- Validate this structured model response against our schema with `contract_validate`
- Check what changed between these two JSON schemas using `schema_diff`
- Inspect the validation failure and get a fix suggestion with `repair_hint`

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