APIM MCP Server Fails to Handle Both URL Parameters and JSON Body in the Same Request

[RahulAgarwal-Illumina]

We are experiencing an issue with the MCP server where it does not handle both URL parameters and a JSON body simultaneously in requests. This issue occurs specifically when the request has the header:

Observations:
-> When a request is sent with Content-Type: application/json and includes a JSON body, URL parameters like cartId are not visible in the MCP Inspector.

-> If the JSON body is removed, the URL parameters like cartId is correctly recognized.

-> Based on inspection using MCP Inspector, this behavior confirms that MCP only handles one input source at a time (either URL parameters or JSON body, but not both).

Impact:
This prevents sending valid requests that include both a required URL parameter and a JSON body payload. As a result, requests fail or behave incorrectly due to missing required parameters.

[Abhiger]

As per my observation only Requests with Query and template parameters work.
Request Headers are converted into MCP tool parameters e.g. Authorization Header
Requests with Json body don't work, irrespective of whether you send it with or without query/Template and header parameters .

[RahulAgarwal-Illumina]

Hey @Abhiger, I tried the JSON body—it's working perfectly even without query or template parameters. The JSON body is being converted into MCP tool parameters. For example, in my case, I used the commerce "AddCartLineRequest" with qty, itemid, and uom, and those are visible in the MCP tool

However, if I add any query or template parameters like cartid, then only those query parameters are shown in the MCP tool, and the JSON body parameters are not.