mcp fix: ext proc returns `method not found`

[Hritik003]

Description:

I've set up a Clickhouse MCP server using the EAI MCP Gateway and wanted to check if this particular behavior is expected.
When I send an initialize handshake to <gateway_url>/mcp using the npx inspector, I'm observing the following error in the extproc logs:

time=2025-11-18T18:50:11.735Z level=ERROR msg="error response from backend" component=mcp-proxy method=logging/setLevel client_gateway_session_id="yMFJ6NqRGtHHIMJnNQJBBs4lVYnR/Ob9AS54JVDNzW2u+G040pBtoIGN9M1loiKiyz8GtDdJm+F301oPg9Qrd9QWGVRTQtS6rFVbff8ZSw9aC4VCzMSND94ZhQC6usqVO8Bk9av5gSjFZgDnGs26USztdRMZt8OpNByuEnfie2ox9arBOjHpaA==" backend=mcp-backend-clickhouse error="Method not found"

The error indicates that the logging/setLevel method is not found on the backend. Is this expected behavior, or should the Clickhouse MCP server be implementing this method?

Repro steps:

Run the Clickhouse mcp server and attach it to the MCP Route backend ref.

Environment:

ext proc image: envoyproxy/ai-gateway-extproc:eb7ded6a00a70cf2dd1f273f71c9909506ca4e89 (latest)
aigw controller image: envoyproxy/ai-gateway-controller:eb7ded6a00a70cf2dd1f273f71c9909506ca4e89 (latest)

cc: @nacx

[nacx]

When the MCP connection is established, in the "initialize" phase, the available features are negotiated. The MCP proxy is returning "logging as supported", and the MCP inspector is trying to set it. Since the ClickHouse MCP doesn't implement that method, that error is returned, and it is safe to ignore.
The MCP proxy returning logging supported is something we do today to cover the case where "some backends support it and some backends don't". We don't have a mechanism today to properly handle features supported "only by a subset of the proxied backends", but this is something that we could probably achieve (it's just not implemented today).