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0mcp generates MCP tools directly from your OpenAPI specification. Simply import your API definition, review the generated tools, and publish your MCP server. Currently, 0mcp supports:
  • OpenAPI 3.x
  • Swagger 2.0
Both JSON and YAML formats are supported.

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Import methods

You can import an API specification in three ways:

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File

Upload a .json, .yaml, or .yml file up to 10 MB.

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URL

Import from a publicly accessible http:// or https:// URL.
The URL must return the OpenAPI document directly without requiring a browser login.

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Paste

Paste the complete OpenAPI document directly into the editor.

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What happens during import?

Before importing, 0mcp analyzes your specification and displays a preview showing:
  • OpenAPI version
  • Server URL
  • Available API operations
From there, you can:
  • Choose which operations become MCP tools
  • Review generated tool names
  • Improve tool descriptions before creating your server
This gives you full control over what AI clients can access.
Review write, delete, administrative, and payment operations carefully before selecting them as tools.

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Writing a high-quality OpenAPI specification

The quality of your MCP server depends on the quality of your OpenAPI document. For the best experience:
  • Give every operation a unique operationId.
  • Write clear summaries and descriptions.
  • Define request parameters and request bodies accurately.
  • Configure authentication using OpenAPI security schemes.
  • Document response schemas.
  • Ensure the server URL points to the correct upstream API.
Well-documented APIs produce more accurate and easier-to-use MCP tools.

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Best practices

  • Use stable, descriptive operationId values, such as get_order instead of get1.
  • Write descriptions that explain what an operation does and when it should be used.
  • Remove deprecated or internal endpoints before exposing them to AI clients.
  • Keep your OpenAPI specification up to date as your API evolves.
If your specification can’t be parsed or validated, see Invalid OpenAPI for common issues and troubleshooting steps.