04.18.2025: Tracing for MCP Client-Server Applications 🔌

Available in Phoenix 8.26+

We’re excited to announce a powerful capability in the OpenInference OSS library openinference-instrumentation-mcp — seamless OTEL context propagation for MCP clients and servers.

What’s New?

This release introduces automatic distributed tracing for Anthropic’s Model Context Protocol (MCP). Using OpenTelemetry, you can now:

• Propagate context across MCP client-server boundaries

• Generate end-to-end traces of your AI system across services and languages

• Gain full visibility into how models access and use external context

The openinference-instrumentation-mcp package handles this for you by:

• Creating spans for MCP client operations

• Injecting trace context into MCP requests

• Extracting and continuing the trace context on the server

• Associating the context with OTEL spans on the server side

Set up

1. Instrument both MCP client and server with OpenTelemetry.

2. Add the openinference-instrumentation-mcp package.

3. Spans will propagate across services, appearing as a single connected trace in Phoenix.

Full example usage is available:

phoenix/tutorials/mcp/tracing_between_mcp_client_and_server at main · Arize-ai/phoenixGitHub

Walkthrough Video

Acknowledgments

Big thanks to Adrian Cole and Anuraag Agrawal for their contributions to this feature.