MCP Resources are incompatible with Claude Code CLI

[CharlieDigital]

Describe the bug

Resources are not discoverable by Claude Code; possibly some format mismatch?

To Reproduce
Steps to reproduce the behavior:

1. Implement a simple resource
2. Check with MCP Inspector; observe that the resource shows up correctly
3. Check in CC CLI; observe that the resource fails to show

Expected behavior

Resource is shown in CC CLI

Logs

Resource is present when working with MCP Inspector:

However, hitting the same endpoint, it is missing in CC:

Kapture.2026-03-06.at.18.47.05.mp4

In VSCP, this is present:

Kapture.2026-03-06.at.18.48.14.mp4

This works correctly with the reference implementation here in Everything Server: https://modelcontextprotocol.io/examples

It appears that there may be some incompatibility with the format CC is expecting?

Additional context

Basic implementation

[McpServerResourceType]
public static class DocumentByKeywordResource
{
    [McpServerResource(
        UriTemplate = "docs://document/{keyword}",
        Name = "Document",
        MimeType = "text/plain"
    )]
    [Description("Get a document by keyword.")]
    public static async Task<ResourceContents> GetDocumentByKeyword(
        string keyword
    )
    {        
        return new TextResourceContents
        {
            Uri = $"docs://document/{keyword}",
            MimeType = "text/plain",
            Text = "Document content goes here",
        };
    }
}

Extracted message from MCP Inspector:

{
  "result": {
    "resourceTemplates": [
      {
        "name": "Document",
        "uriTemplate": "docs://document/{keyword}",
        "description": "Get a document by keyword.",
        "mimeType": "text/plain"
      }
    ]
  },
  "id": 3,
  "jsonrpc": "2.0"
}

Note: server is in sessionless mode.

[stephentoub]

Same as #1261, where the conclusion is that Claude likely simply lacks such support?

[CharlieDigital]

I reviewed that issue; not certain since this is failing to list the resources altogether.

However, because their reference @modelcontextprotocol/server-everything does list resources, it would seem that it should work?

Unfortunately cannot yet capture the response stream; still trying to see if I can get a delta on the response.

[CharlieDigital]

Payload from the reference Everything server

{
  "result": {
    "resourceTemplates": [
      {
        "name": "Dynamic Text Resource",
        "uriTemplate": "demo://resource/dynamic/text/{resourceId}",
        "mimeType": "text/plain",
        "description": "Plaintext dynamic resource fabricated from the {resourceId} variable, which must be an integer."
      },
      {
        "name": "Dynamic Blob Resource",
        "uriTemplate": "demo://resource/dynamic/blob/{resourceId}",
        "mimeType": "application/octet-stream",
        "description": "Binary (base64) dynamic resource fabricated from the {resourceId} variable, which must be an integer."
      }
    ]
  },
  "jsonrpc": "2.0",
  "id": 4
}

No delta that I can see

[CharlieDigital]

I see the problem; Claude doesn't display resource templates at all 🤦‍♂️

Adding this properly exposes resources

    .WithListResourcesHandler(
        async (context, ct) =>
        {
            return new ListResourcesResult()
            {
                Resources =
                [
                    new Resource()
                    {
                        Name = "Document",
                        Uri = "docs://document/test",
                        MimeType = "text/plain",
                    },
                ],
            };
        }
    )