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OpenAPI to MCP Tool Converter
x402
OpenAPI to MCP Tool Converter is a paid API for AI agents from modell.halowerk.com, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-15).
Converts an OpenAPI 3.x document into a set of MCP tool definitions, merging path/query/header parameters and request body into a single flat input schema per operation with inline-expanded $refs.
Price / call$0.002
Success—
StatusUnknown
How this service works
Converts each OpenAPI operation into an MCP tool. Path, query and header parameters and the JSON request body are merged into one input schema, because MCP tools take exactly one; a name collision between a body field and a parameter is reported rather than silently overwritten. Internal $refs are expanded inline so each tool schema stands alone — an MCP client cannot resolve them.
Output
A set of MCP tool definitions — one per OpenAPI operation — where each tool has a single flat input schema combining all path, query, header parameters and the JSON request body fields. All internal $refs are expanded inline so each schema is self-contained. Any name collisions between body fields and parameters are reported as errors rather than silently overwritten.
Example use cases
Expose REST API to AI agents
“I have an OpenAPI 3 spec for my payments API and I want to make it available as MCP tools so my AI agent can call it — can you convert the spec into MCP tool definitions with all parameters merged into one input schema?”
Inline $refs for standalone tool schemas
“My OpenAPI spec uses a lot of $ref references throughout the schemas — convert it to MCP tools and expand all those $refs inline so each tool schema is completely self-contained and doesn't need external resolution.”
Detect parameter and body name collisions
“Before I ship my OpenAPI-to-MCP integration, can you run my spec through the converter and tell me if any of my path, query, or header parameter names clash with fields in the request body?”
Technical details
Endpoint
POSThttps://modell.halowerk.com/v1/openapi-to-mcpWhen to prefer
Use this endpoint when you need to expose an existing OpenAPI 3.x API to MCP clients or AI agents and want each operation represented as a standalone MCP tool with a single, flat, fully self-contained input schema. It is the right choice when your spec uses $refs that MCP clients cannot resolve, or when you need explicit collision detection between parameter names and body fields rather than silent overwrites.
Side effects
- Invalid or malformed OpenAPI 3.x document causes parsing failure
- Unsupported OpenAPI version (e.g. Swagger 2.x) returns an error
- Circular $ref references may cause expansion failures or infinite loops
- Name collisions between body fields and parameters are reported as errors and may block conversion
- Missing required openapi/info/paths fields cause validation errors
- Extremely large specs may time out or exceed payload limits
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| naming | string | How to normalise tool names. |
| prefix | string | Prefix for every tool name, to keep several APIs apart in one client. |
| document | object | The OpenAPI 3.x document as JSON. |
| include_methods | array | Only convert these HTTP methods, e.g. ["get"] for a read-only server. |
Tags
x402
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