Quickly verify your client can call a remote MCP tool

This service runs an unauthorized MCP server exposing a single tool: revealsecret. Call it from your client to get a small proof that a real MCP round‑trip worked.

Use with OpenAI Playground (Flows) Use with OpenAPI (Open WebUI)

OpenAI Playground (Flows)

Point your Flow’s MCP tool to this SSE endpoint, then invoke revealsecret to confirm connectivity.

MCP SSE endpoint

https://mcptest.xyz/sse

Authorization: set to None or provide any token — it is not checked.
Add the tool and call revealsecret; you should see a short success string.

OpenAPI (Open WebUI)

Import the OpenAPI spec URL, then run the operation that maps to revealsecret.

OpenAPI spec URL

https://mcptest.xyz/openapi.json

Authorization: set to None or use any token — it’s ignored.
Run POST /reveal_secret; on success, you’ll receive a small “secret”.

The spec exposes /reveal_secret (POST) and related schemas [1].

OpenAI vs OpenAPI — don’t mix them up

OpenAI

Company/products (e.g., Playground, Flows). Here, you configure a Flow tool that talks MCP over HTTP/S via SSE.

OpenAPI

An API description format (formerly Swagger). Tools like Open WebUI can import an OpenAPI spec to call HTTP endpoints.

They differ by one letter, but they’re unrelated concepts here. Use the left endpoint for OpenAI Playground Flows, and the right spec URL for OpenAPI-based clients.

What to expect

Success: calling revealsecret returns a short confirmation string.
If your client can’t list or call the tool, check your endpoint URL and network access.
Anything else unexpected? Please file an issue with details.

Why this exists

To make it fast and safe to verify remote MCP flow support without wiring up credentials or a full stack.

This is a “pure” Go implementation using the standard library (no frameworks), so it’s easy to read and tweak the flow [1].