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MCP connectivity
MCP observability

MCP observability

Review MCP-specific metrics, logs, and traces.

Before you begin

Complete an MCP guide, such as the stdio guide. This guide uses the agentgateway playground to interact with an MCP tool server, which generates metrics, logs, and traces.

View MCP metrics

You can access the agentgateway metrics endpoint to view MCP-specific metrics, such as the number of tool calls that were performed.

  1. Open the agentgateway metrics endpoint.
  2. Look for the list_calls_total metric. This metric shows the number of tool calls that were performed and includes important information about the call, such as:
    • server: The MCP server that was used for the tool call.
    • name: The name of the tool that was used.

View traces

  1. Use docker compose to spin up a Jaeger instance with the following components:

    • An OpenTelemetry collector that receives traces from the agentgateway. The collector is exposed on http://localhost:4317.
    • A Jaeger agent that receives the collected traces. The agent is exposed on http://localhost:14268.
    • A Jaeger UI that is exposed on http://localhost:16686.
    docker compose -f - up -d <<EOF
services:
  jaeger:
    container_name: jaeger
    restart: unless-stopped
    image: jaegertracing/all-in-one:latest
    ports:
    - "127.0.0.1:16686:16686"
    - "127.0.0.1:14268:14268"
    - "127.0.0.1:4317:4317"
    environment:
    - COLLECTOR_OTLP_ENABLED=true

EOF

  2. Configure your agentgateway proxy to emit traces and send them to the built-in OpenTelemetry collector agent.

    cat <<EOF > config.yaml
config:  
  tracing:
    otlpEndpoint: http://localhost:4317
    randomSampling: true
binds:
- port: 3000
  listeners:
  - routes:
    - policies:
        cors:
          allowOrigins:
            - "*"
          allowHeaders:
            - mcp-protocol-version
            - content-type
            - cache-control
      backends:
      - mcp:
          targets:
          - name: everything
            stdio:
              cmd: npx
              args: ["@modelcontextprotocol/server-everything"]
EOF

  3. Run your agentgateway proxy.

    agentgateway -f config.yaml

  4. Open the agentgateway playground and click Connect. Then, select a tool, such as echo, enter any message, and click Run Tool.

  5. Open the Jaeger UI and select the call_tool operation. Then, verify that you can see traces for your MCP tool call.

View logs

Agentgateway automatically logs information to stdout. When you run agentgateway on your local machine, you can view a log entry for each request that is sent to agentgateway in your CLI output.

Example for a successful MCP tool call:

2025-09-04T20:01:40.493660Z	info	mcp::sse	new client message for /sse	
session_id="6b497ee9-3710-428a-96d2-31ebeab73dcd"Request(JsonRpcRequest 
{ jsonrpc: JsonRpcVersion2_0, id: Number(4), request: CallToolRequest(Request
{ method: CallToolRequestMethod, params: CallToolRequestParam { name: "echo", 
arguments: Some({"message": String("hello world")}) }, extensions: Extensions }) })
MCP authorization