Observability

Every MCP request goes through, from the outermost:

the OpenTelemetry instrumentation, following the MCP semantic conventions,
the request log,
the panic recovery,
the tool, resource or prompt handler.

With the streamable HTTP transport, the HTTP requests are also instrumented with otelhttp: a POST /mcp server span, and the http.server.* metrics.

Traces

Each MCP request gets a server span, child of the POST /mcp HTTP span:

named {mcp.method.name} {target}: tools/call greet, resources/read docs://readme, prompts/get review, or just the method without target: tools/list,
with the attributes:

Attribute	Example	When
`mcp.method.name`	`tools/call`	always
`mcp.session.id`	`4XZ…`	with a session
`gen_ai.operation.name`	`execute_tool`	tool calls
`gen_ai.tool.name`	`greet`	tool calls
`gen_ai.prompt.name`	`review`	`prompts/get`
`mcp.resource.uri`	`docs://readme`	`resources/read`
`error.type`	`tool_error`, `-32602`, `_OTHER`	failures

with an error status when the request fails: error.type is the JSON-RPC error code for protocol errors (unknown tool, invalid params…), _OTHER for other errors (a panic…), and tool_error for a tool returning an error result.

When the client sends a trace context in the request _meta (traceparent, tracestate), as advised by the conventions, the span continues the trace of the client instead. Spans created in handlers with ctx are children of the MCP span.

Metrics

Metric	Description	Attributes
`mcp.server.operation.duration`	Duration of the MCP requests, in seconds	`mcp.method.name`, `gen_ai.tool.name`, `gen_ai.prompt.name`, `error.type`

The instrumentation scope of the spans and metrics is github.com/go-oryn/oryn/mcpserver.

Logs

Each request is logged as mcp request, at error level for failures and tool errors, and info level otherwise, with:

Attribute	Example
`method`	`tools/call`
`target`	`greet`
`session_id`	`4XZ…`
`duration`	`1.2ms`
`error_type`	`tool_error` (failures only)
`error`	`missing name` (failures only)

The log is correlated with the request span. Disable request logs with mcpserver.log.enabled: false. The logs of the MCP SDK itself (sessions connecting…) are logged at debug level.

Exclude methods

Noisy methods can be excluded from spans, metrics and request logs:

mcpserver:
  observability:
    exclude:
      - ping
      - notifications/initialized