[nik13]

Summary

Correct the MCP package README's claim that the propagation instrumentor automatically traces all requests. MCPInstrumentor creates no spans. Recommend MCP 2.3+ native OpenTelemetry for new Python setups and retain the released MCP 1.x propagation/lifecycle instructions.

• Link the runnable native guide in docs(mcp): add native Python client and server tracing guide docs#1087 (merge the guide before this README link).
• Remove unnecessary OpenAI installation/key requirements from the propagation setup.
• Explain native error-content controls and the difference between propagation and span creation.
• Add a failing-first README contract test. No runtime code, package constraints, version, or release mapping changes.

Validation

All Python test processes ran under a macOS outbound-network-denied sandbox, with loopback allowed and a scrubbed environment.

• Before: the new test fails on the automatic-all-requests sentence.
• After: 48 tests pass on MCP 1.8.1 + Pydantic 2.11.10, and 48 pass on latest MCP 2.3.0. These include real stdio/HTTP lifecycle, propagation, tuple compatibility, and dependency tests. The floor has the known upstream lifespan forward-reference warning.
• The companion native guide's exact snippets pass against a loopback OTLP/HTTP protobuf receiver in fresh environments without traceAI, on Python 3.11 and 3.13. It checks successful and failing tool calls, four concurrent calls, one client/server pair per tool call, propagated IDs/parentage, tool attributes, project resources, synthetic auth headers, and shutdown export.
• release_plan.py --check: 129 packages consistent. git diff --check passes.

Existing work and limits

#311 already merged the runtime repairs proposed in #221/#222; current-dev tests confirm those defects no longer reproduce. This PR does not repeat or alter those fixes, TypeScript #403/#482, or the separate Python FastMCP package guide.

Only published dependencies are used (MCP 2.3.0 and traceAI-mcp 0.1.3 verified on PyPI). No registry publish, workflow dispatch, merge, real credentials, or Cloud ingestion/UI test was performed. Native tool classification was checked against the backend's execute_tool mapping; loopback export is not a claim of live Cloud acceptance. No product E2E applies to a package README-only change.

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