Observability

Every MCP request goes through, from the outermost:

1. the timeout, if configured,
2. the OpenTelemetry instrumentation, following the MCP semantic conventions,
3. the request log,
4. the transport.

With the streamable HTTP transport, the HTTP requests are also instrumented with otelhttp: an HTTP client span per request, and the http.client.* metrics.

Traces

Each MCP request gets a client span, child of the span of ctx:

• named {mcp.method.name} {target}: tools/call search, 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	search	tool calls
gen_ai.prompt.name	review	prompts/get
mcp.resource.uri	docs://readme	resources/read
server.address	docs.example.com	streamable HTTP
server.port	443	streamable HTTP
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 (timeout, connection…), and tool_error for a tool returning an error result.

Propagation

The trace continues on the server, in two ways:

• the trace context (traceparent, tracestate) is put in the request _meta, as advised by the conventions: the MCP server span of an mcpserver is a child of the client span, whatever the transport,
• with streamable HTTP, the HTTP requests carry the trace context headers too.

The application propagator is used, so OTEL_PROPAGATORS applies.

Metrics

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

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

Logs

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

Attribute	Example
server	docs, the server name
method	tools/call
target	search
session_id	4XZ…
duration	1.2ms
error_type	tool_error (failures only)
error	missing query (failures only)

The log is correlated with the request span. Disable request logs with mcpclient.log.enabled: false. The logs of the MCP SDK itself are logged at debug level.

Exclude methods

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

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