MCP-DEP-002

logging/setLevel is no longer implemented

“Log level is now set per-request via io.modelcontextprotocol/logLevel in _meta; servers MUST NOT emit notifications/message for requests that did not include this field.” — spec anchor

How to fix this

Remove `logging/setLevel`. Log level is now set per request via `io.modelcontextprotocol/logLevel` in `_meta`, and a server must not emit `notifications/message` for a request that did not include that field.

Example: failing and passing

The server still accepts logging/setLevel, which was removed in favour of a per-request log level in _meta.

Violates MCP-DEP-002 · HTTP

POST /mcp HTTP/1.1
Host: mcp.example.com
Content-Type: application/json
Mcp-Method: logging/setLevel
MCP-Protocol-Version: 2026-07-28

{"jsonrpc":"2.0","id":1,"method":"logging/setLevel","params":{"level":"info","_meta":{"io.modelcontextprotocol/protocolVersion":"2026-07-28","io.modelcontextprotocol/clientCapabilities":{}}}}

HTTP/1.1 200 OK
Content-Type: application/json

{"jsonrpc":"2.0","id":1,"result":{"resultType":"complete"}}

The server treats logging/setLevel as an unknown method: 404 with JSON-RPC error -32601.

Complies with MCP-DEP-002 · HTTP

POST /mcp HTTP/1.1
Host: mcp.example.com
Content-Type: application/json
Mcp-Method: logging/setLevel
MCP-Protocol-Version: 2026-07-28

{"jsonrpc":"2.0","id":1,"method":"logging/setLevel","params":{"level":"info","_meta":{"io.modelcontextprotocol/protocolVersion":"2026-07-28","io.modelcontextprotocol/clientCapabilities":{}}}}

HTTP/1.1 404 Not Found
Content-Type: application/json

{"jsonrpc":"2.0","id":1,"error":{"code":-32601,"message":"Method not found"}}

Check your own server against MCP-DEP-002

Probe P4.3 checks MCP-DEP-002 in the same request as 3 other rules, so one run shows your server's result for this rule next to the rest. Validate a server or read how the validator works.

Background on this topic: the 2026-07-28 migration guide.

Other Deprecated and removed features rules

MCP-DEP-001ping is no longer implemented
MCP-DEP-003resources/subscribe and resources/unsubscribe replaced by subscriptions/listen
MCP-DEP-004No legacy HTTP+SSE endpoint is served
MCP-DEP-005Roots / Sampling / Logging capabilities are not advertised
MCP-DEP-006Server accepts initialize (dual-era support)
MCP-DEP-007A modern-only server names its supported versions in the initialize error