Server capabilities not affecting the stream of "{capability}/list" requests and "method not found" errors.

[jakenuts]

Describe the bug
If you review the mcp diagnostic logs of basically any server (at least all the ones I've seen) they are littered with requests for capability lists and then "method not found" errors. It seems like the mcp client should read the capbilities once and then not query the undefined ones every couple seconds.

To Reproduce
Steps to reproduce the behavior:

1. Write a typescript mcp server that only has "tools" and pass the capabilities to the client
2. Run Claude Desktop and then view the logs in Claude\logs.

Expected behavior
If a server indicates it supports a certain capability, perhaps the available options should be checked periodically. But if it lists a capability as undefined or doesn't otherwise indicate it supports prompts, resources, that should end the conversation until the client configuration is reloaded.

Logs
If applicable, add logs to help explain your problem.
2025-02-19T20:35:34.178Z [mssql] [info] Message from client: {"method":"resources/list","params":{},"jsonrpc":"2.0","id":29}
2025-02-19T20:35:34.181Z [mssql] [info] Message from server: {"jsonrpc":"2.0","id":29,"error":{"code":-32601,"message":"Method not found"}}
2025-02-19T20:35:34.185Z [mssql] [info] Message from client: {"method":"prompts/list","params":{},"jsonrpc":"2.0","id":30}
2025-02-19T20:35:34.186Z [mssql] [info] Message from server: {"jsonrpc":"2.0","id":30,"error":{"code":-32601,"message":"Method not found"}}
2025-02-19T20:35:39.175Z [mssql] [info] Message from client: {"method":"resources/list","params":{},"jsonrpc":"2.0","id":31}
2025-02-19T20:35:39.177Z [mssql] [info] Message from server: {"jsonrpc":"2.0","id":31,"error":{"code":-32601,"message":"Method not found"}}
2025-02-19T20:35:39.181Z [mssql] [info] Message from client: {"method":"prompts/list","params":{},"jsonrpc":"2.0","id":32}
2025-02-19T20:35:39.181Z [mssql] [info] Message from server: {"jsonrpc":"2.0","id":32,"error":{"code":-32601,"message":"Method not found"}}
2025-02-19T20:35:44.181Z [mssql] [info] Message from client: {"method":"resources/list","params":{},"jsonrpc":"2.0","id":33}
2025-02-19T20:35:44.186Z [mssql] [info] Message from server: {"jsonrpc":"2.0","id":33,"error":{"code":-32601,"message":"Method not found"}}
2025-02-19T20:35:44.193Z [mssql] [info] Message from client: {"method":"prompts/list","params":{},"jsonrpc":"2.0","id":34}
2025-02-19T20:35:44.196Z [mssql] [info] Message from server: {"jsonrpc":"2.0","id":34,"error":{"code":-32601,"message":"Method not found"}}
`

[disintegrator]

Noticed this as well because my mcp.log and the .log files were growing over time. Also using the high-level server. Stab in the dark but I don't think this bug is in the MCP SDK but rather the Claude app polling with prompts/list and resources/list.

I tried not advertising prompts and resources capabilities and setting listChanged and subscribe to false where appropriate. I also tried registering some noop resources and prompts. None of it was stopping the polling activity and growing logs.

[adenot]

After some investigation, this is what I found...

When the mcp inspector calls tools/list, the JSONRPC looks like:

{"jsonrpc":"2.0","id":2,"method":"tools/list","params":{}}

Which returns the tools list successfuly.

But when python-sdk calls, it omits the params key:

{"method":"tools/list","jsonrpc":"2.0","id":1}

And this results on a "Method not found" error when calling an MCP server using this SDK.

From the jsonrpc documentation, the params key should be optional, so that leads me to believe that it could be a bug with this SDK.

For my tests I was using:

(python mcp client)
pydantic-ai=0.0.43
mcp=1.4.1

(typescript mcp server - https://github.com/aaronsb/confluence-cloud-mcp)
modelcontextprotocol/sdk: 1.6.0