Is Zod Contract Mock Forge free?

Yes, Zod Contract Mock Forge is free to use.

How do I install Zod Contract Mock Forge?

Zod Contract Mock Forge is a local plugin. Install it using npm package: zod-contract-mock-forge-mcp and add the generated configuration snippet to your AI app's MCP config file. Then restart your AI app.

Is Zod Contract Mock Forge safe to use?

Yes. Zod Contract Mock Forge passed MCP Marketplace's automated security scan with a score of 7.2/10 (low risk). Every server on MCP Marketplace is security-scanned before it's listed; see the full security report on this page for the findings and permissions.

What AI apps work with Zod Contract Mock Forge?

Zod Contract Mock Forge uses the Model Context Protocol (MCP) and works with any MCP-compatible AI app, including Claude, ChatGPT / Codex, Gemini, Copilot, Cursor, and more.

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Zod Contract Mock Forge MCP Server

by vola-trebla

Developer ToolsModerate7.2Local

Free

MCP server for deterministic mock generation and API contract scaffolding using Zod schemas

About

MCP server for deterministic mock generation and API contract scaffolding using Zod schemas

Security Report

7.2

Moderate7.2Low Risk

A well-structured MCP server for Zod schema testing with clean separation of concerns and proper input validation. No authentication is required (appropriate for developer tools), and the server's permissions align with its purpose: file I/O for schema analysis, limited subprocess execution (git), and deterministic mock generation. One moderate-severity finding regarding unsanitized git commands in schema evolution features warrants attention, but the overall codebase is secure and maintainable. Package verification found 1 issue.

4 files analyzed · 5 issues found

Security scores are indicators to help you make informed decisions, not guarantees. Always review permissions before connecting any MCP server.

Permissions Required

This plugin requests these system permissions. Most are normal for its category.

File System Read

Reads files on your machine. Normal for tools that analyze or process local data.

File System Write

Writes or modifies files on your machine. Check that this is expected for the tool.

HTTP Network Access

Connects to external APIs or services over the internet.

Shell Command Execution

Runs commands on your machine. Be cautious — only use if you trust this plugin.

env_vars

Check that this permission is expected for this type of plugin.

How to Install

Add this to your MCP configuration file:

{
  "mcpServers": {
    "io-github-vola-trebla-zod-contract-mock-forge-mcp": {
      "args": [
        "-y",
        "zod-contract-mock-forge-mcp"
      ],
      "command": "npx"
    }
  }
}

Documentation

View on GitHub

From the project's GitHub README.

zod-contract-mock-forge-mcp

An MCP server that turns Zod schemas into mocks, violations, and contract tests — so your AI agent can reason about API contracts without manually crafting payloads.

The Problem

Zod schemas are runtime code. An AI agent cannot execute them, introspect their constraints, or generate valid/invalid payloads without this layer. The agent also cannot detect when the schema and the OpenAPI docs silently diverged, or whether a schema change breaks existing test fixtures.

Tools

Mock generation

Tool	Arguments	What it returns
`generate_valid_mock`	`schema_code`, `count?`	Valid mock data matching the schema
`generate_mock_variants`	`schema_code`, `count?`, `seed?`	N structurally valid but value-diverse mocks — for property-based testing

Violation generation

Tool	Arguments	What it returns
`generate_boundary_violations`	`schema_code`	Invalid payloads for each constraint: missing fields, type mismatches, min/max, email/uuid/url
`generate_exhaustive_union_violations`	`schema_code`	Per-variant violations for every branch of a `z.union()` or `z.discriminatedUnion()`

Schema analysis

Tool	Arguments	What it returns
`introspect_schema`	`schema_code`	JSON Schema representation — for LLM understanding of the contract
`read_schema_from_file`	`file_path`, `export_name?`	Extracts the Zod schema expression from a TypeScript/JS file
`detect_schema_drift`	`zod_file_path`, `schema_export_name`, `openapi_file_path`, `openapi_schema_name?`	Diffs Zod vs OpenAPI — reports `missing_in_openapi`, `missing_in_zod`, `type_conflict`, `required_mismatch`
`evaluate_schema_evolution`	`schema_file_path`, `schema_export_name`, `old_schema_content?`	Generates mocks from old schema, validates against new — detects breaking changes before tests run

Contract testing

Tool	Arguments	What it returns
`scaffold_api_contract_test`	`framework`, `base_url`, `endpoint`, `method`, `schema_code`, `test_name?`	Contract test boilerplate for Playwright, Jest, Vitest, or MSW
`suggest_contract_fix`	`schema_code`, `payload`	Validates a JSON payload and explains each violation with a fix suggestion

Setup

1. Install

npm install -g zod-contract-mock-forge-mcp

2. Add to your editor

Cursor / VS Code (`.cursor/mcp.json` or `.vscode/mcp.json`)

{
  "mcpServers": {
    "zod-forge": {
      "command": "zod-contract-mock-forge-mcp"
    }
  }
}

Claude Code

claude mcp add zod-forge zod-contract-mock-forge-mcp

Example usage

My schema file is src/schemas/user.ts, exported as UserSchema.
My OpenAPI spec is docs/openapi.yaml.

1. introspect_schema — what are the constraints on this schema?
2. generate_mock_variants — give me 10 diverse valid payloads (seed: 42) for CI reproducibility
3. generate_exhaustive_union_violations — test every branch of the role discriminated union
4. detect_schema_drift — has the Zod schema diverged from the OpenAPI docs?
5. evaluate_schema_evolution — does my schema change break any existing mock data?

Example output

generate_mock_variants — 3 diverse valid mocks, seeded for CI:

{
  "schema_id": "schema_a1b2c3d4",
  "count": 3,
  "all_valid": true,
  "variants": [
    { "name": "Colleen Rowe", "age": 37 },
    { "name": "Pat Reynolds", "age": 24 },
    { "name": "Veronica Konopelski", "age": 45 }
  ]
}

detect_schema_drift — field missing in OpenAPI, extra field in Zod:

{
  "drift_count": 2,
  "drifts": [
    {
      "field_path": "role",
      "drift_type": "missing_in_openapi",
      "zod_value": "string",
      "openapi_value": null
    },
    {
      "field_path": "email",
      "drift_type": "missing_in_zod",
      "zod_value": null,
      "openapi_value": "string"
    }
  ]
}

evaluate_schema_evolution — new required field breaks existing mocks:

{
  "breaking_change": true,
  "sample_count": 20,
  "invalid_mock_count": 20,
  "failure_reasons": [
    {
      "field_path": "status",
      "zod_code": "invalid_type",
      "expected": "string",
      "received": "undefined",
      "affected_mock_count": 20
    }
  ]
}

Scripts

npm run build        # compile TypeScript → dist/
npm run lint         # ESLint
npm run format       # Prettier --write
npm run format:check # Prettier check (used in CI)
npm test             # Vitest