Align telemetry with OpenTelemetry MCP semantic conventions #1139

Copilot · 2026-01-12T18:06:52Z

Update attribute names to match new MCP semantic conventions
Add missing attributes: mcp.protocol.version, network.protocol.name
Fix span name to follow format {mcp.method.name} {target}
Implement outer GenAI activity detection (client side only)
Update histogram bucket boundaries
Update tests

PR Feedback Addressed

Original prompt

The pr @open-telemetry/semantic-conventions/pull/2083 adds a standard convention for mcp. This repo implements an older attempt at such a convention. Please go through the new standard convention in detail and ensure it's fully implemented in the Modelcontextprotocol.Core library with 100% compatibility and interoperability.

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…en-telemetry/semantic-conventions#2083 - Change mcp.tool.name to gen_ai.tool.name - Change mcp.prompt.name to gen_ai.prompt.name - Change mcp.request.id to jsonrpc.request.id - Change rpc.jsonrpc.error_code to rpc.response.status_code - Update network.transport values from 'stdio' to 'pipe' and 'sse'/'http' to 'tcp' - Add gen_ai.operation.name attribute (value: 'execute_tool' for tools/call) - Update histogram bucket boundaries to match semantic conventions spec - Update tests to verify new attribute names Co-authored-by: stephentoub <[email protected]>

stephentoub · 2026-01-12T20:00:29Z

@copilot:

Is the span name correct? It looks like the activity is currently being created with the name of the method rather "Span name SHOULD follow the format {mcp.method.name} {target} where target SHOULD match {gen_ai.tool.name} or {gen_ai.prompt.name} when applicable. If there is no low-cardinality target available, the Span name SHOULD be {mcp.method.name}."
Where is mcp.protocol.version being set? Where is network.protocol.name being set? Etc. Please re-review https://github.com/open-telemetry/semantic-conventions/blob/main/docs/gen-ai/mcp.md#recording-mcp-transport and ensure that every property called out is either being set or that there's a good reason it's being excluded (which should be noted in a comment).
The spec calls out "If the MCP instrumentation can reliably detect that outer GenAI instrumentation is already tracing the tool execution, it SHOULD NOT create a separate span. Instead, it SHOULD add MCP-specific attributes to the existing tool execution span." If these tools are being used as AIFunctions, and are being invoked from a FunctionInvokingChatClient with Microsoft.Extensions.AI, then there may already be an active Activity for this. Please look for it and update that activity with the additional properties rather than creating a new one.

…t outer GenAI activity - Fix span name to follow format "{mcp.method.name} {target}" per semantic conventions - Add mcp.protocol.version attribute to telemetry after initialization - Add network.protocol.name attribute for HTTP transports - Implement outer GenAI activity detection for tool calls (avoid duplicate spans) - Add NegotiatedProtocolVersion property to McpSessionHandler for telemetry - Propagate protocol version from client/server impl to session handler - Update tests to verify mcp.protocol.version attribute Co-authored-by: stephentoub <[email protected]>

Copilot · 2026-01-12T20:18:25Z

@copilot:

Is the span name correct? It looks like the activity is currently being created with the name of the method rather "Span name SHOULD follow the format {mcp.method.name} {target} where tar...

Addressed in eecac8d:

Span name: Fixed to follow format {mcp.method.name} {target} - the activity is now created with the correct name upfront via CreateActivityName(method, target).
Missing attributes:
- Added mcp.protocol.version - propagated from client/server after initialization to the session handler
- Added network.protocol.name for HTTP transports (value: "http")
- Other attributes like server.address/server.port noted with TODOs as they require transport-level information not currently available
Outer GenAI activity detection: Added TryGetOuterToolExecutionActivity() that checks if Activity.Current has gen_ai.operation.name = execute_tool. When detected, MCP-specific attributes are added to that activity instead of creating a new span.

stephentoub

@copilot, please iterate through https://github.com/open-telemetry/semantic-conventions/blob/main/docs/gen-ai/mcp.md in detail, validating every statement / requirement against this implementation. You might want to first emit a file containing a todo list for every individual requirement in that spec, and then iterate through that todo list validating each; just make sure to delete that temporary todo list file when you're done.

src/ModelContextProtocol.Core/McpSessionHandler.cs

src/ModelContextProtocol.Core/Diagnostics.cs

- Change default network.transport from "pipe" to "unknown" for unsupported transports - Convert NegotiatedProtocolVersion to auto-property - Only look for outer GenAI activity on CLIENT side, not SERVER side - Move ExtractTargetFromMessage calls into ShouldInstrumentMessage blocks - Remove "Per semantic conventions" comments - Delete ShortSecondsBucketBoundaries, rename to ExplicitBucketBoundaries - Change TryGetOuterToolExecutionActivity to check activity.OperationName - Add test for FunctionInvokingChatClient span augmentation Co-authored-by: stephentoub <[email protected]>

Copilot · 2026-01-12T21:49:54Z

@copilot, please iterate through https://github.com/open-telemetry/semantic-conventions/blob/main/docs/gen-ai/mcp.md in detail, validating every statement / requirement against this implementation. Yo...

Completed in 44cf972 - created a detailed todo checklist in /tmp/mcp-semantic-conventions-todo.md, validated each requirement against the implementation, made necessary fixes, and deleted the file. Key findings:

Validated and implemented:

Context propagation via params._meta ✓
Span naming format {mcp.method.name} {target} ✓
All required/conditionally required attributes ✓
Outer GenAI activity detection (client-side only) ✓
Histogram bucket boundaries ✓

Noted for future work (marked as Recommended, not Required):

server.address/server.port and client.address/client.port require transport-layer information
network.protocol.version could be added for HTTP transports
jsonrpc.protocol.version is always "2.0" so not needed

src/ModelContextProtocol.Core/Diagnostics.cs

src/ModelContextProtocol.Core/McpSessionHandler.cs

stephentoub · 2026-01-12T22:58:05Z

cc: @lmolkova

…e comments, use pattern matching - Invert if statement in TryGetOuterToolExecutionActivity to avoid multiple return false - Remove "Per MCP" comment in McpSessionHandler - Use pattern matching `is "tcp"` instead of `== "tcp"` - Remove redundant DisplayName setting (StartActivity already sets it via CreateActivityName) Co-authored-by: stephentoub <[email protected]>

src/ModelContextProtocol.Core/McpSessionHandler.cs

The parameter was only used for DisplayName setting which was removed as redundant. Co-authored-by: stephentoub <[email protected]>

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tarekgh · 2026-01-13T19:02:22Z

@copilot there are two test failures in the CI. Looks the first is credible.

CC @stephentoub

[xUnit.net 00:01:57.26]     ModelContextProtocol.Tests.DiagnosticTests.Session_TracksActivities [FAIL]
Data collector 'Blame' message: All tests finished running, Sequence file will not be generated.
  Failed ModelContextProtocol.Tests.DiagnosticTests.Session_TracksActivities [135 ms]
  Error Message:
   Assert.Single() Failure: The collection did not contain any matching items
Expected:   (predicate expression)
Collection: [Activity { ActivityTraceFlags = Recorded, Baggage = [], Context = System.Diagnostics.ActivityContext, DisplayName = "initialize", Duration = 00:00:00.0006470, ··· }, Activity { ActivityTraceFlags = Recorded, Baggage = [], Context = System.Diagnostics.ActivityContext, DisplayName = "initialize", Duration = 00:00:00.0043991, ··· }, Activity { ActivityTraceFlags = Recorded, Baggage = [], Context = System.Diagnostics.ActivityContext, DisplayName = "notifications/initialized", Duration = 00:00:00.0001142, ··· }, Activity { ActivityTraceFlags = Recorded, Baggage = [], Context = System.Diagnostics.ActivityContext, DisplayName = "tools/list", Duration = 00:00:00.0001837, ··· }, Activity { ActivityTraceFlags = Recorded, Baggage = [], Context = System.Diagnostics.ActivityContext, DisplayName = "notifications/initialized", Duration = 00:00:00.0000079, ··· }, ···]
  Stack Trace:
     at ModelContextProtocol.Tests.DiagnosticTests.Session_TracksActivities() in /_/tests/ModelContextProtocol.Tests/DiagnosticTests.cs:line 50
--- End of stack trace from previous location ---
Results File: /home/runner/work/csharp-sdk/csharp-sdk/artifacts/testresults/_runnervmi13qx_2026-01-12_23_19_41.trx

Waiting 10 seconds for foreground threads to exit...
   at Xunit.v3.TestProcessLauncherAdapter.GetAssemblyInfo(ITestProcessLauncher launcher, XunitProjectAssembly projectAssembly)
   at Xunit.v3.TestProcessLauncherAdapter.GetAssemblyInfo(XunitProjectAssembly projectAssembly)
   at Xunit.Runner.v3.Xunit3..ctor(XunitProjectAssembly projectAssembly, ISourceInformationProvider sourceInformationProvider, IMessageSink diagnosticMessageSink, ITestProcessLauncher testProcessLauncher)
   at Xunit.Runner.v3.Xunit3.ForDiscoveryAndExecution(XunitProjectAssembly projectAssembly, ISourceInformationProvider sourceInformationProvider, IMessageSink diagnosticMessageSink, ITestProcessLauncher testProcessLauncher)
   at Xunit.XunitFrontController.Create(XunitProjectAssembly projectAssembly, ISourceInformationProvider sourceInformationProvider, IMessageSink diagnosticMessageSink, ITestProcessLauncher testProcessLauncher)
   at Xunit.Runner.VisualStudio.VsTestRunner.RunTestsInAssembly(IRunContext runContext, IFrameworkHandle frameworkHandle, LoggerHelper logger, TestPlatformContext testPlatformContext, RunSettings runSettings, IMessageSink reporterMessageHandler, AssemblyRunInfo runInfo)
   at Xunit.Runner.VisualStudio.VsTestRunner.RunTestsInAssembly(IRunContext runContext, IFrameworkHandle frameworkHandle, LoggerHelper logger, TestPlatformContext testPlatformContext, RunSettings runSettings, IMessageSink reporterMessageHandler, AssemblyRunInfo runInfo)
Data collector 'Blame' message: All tests finished running, Sequence file will not be generated.
Results File: D:\a\csharp-sdk\csharp-sdk\artifacts\testresults\runneradmin_runnervmybtk3_2026-01-13_17_03_41.trx

tarekgh

Other than failing tests, LGTM!

stephentoub · 2026-01-14T02:08:28Z

Other than failing tests, LGTM!

Thanks. I've seen that failure before; we have some kind of non-determinism in our tests we need to root out.

Initial plan

82204d5

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Copilot AI changed the title ~~[WIP] Add implementation of new MCP standard conventions~~ Align telemetry with OpenTelemetry MCP semantic conventions Jan 12, 2026

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src/ModelContextProtocol.Core/McpSessionHandler.cs Show resolved Hide resolved

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Remove unused usingOuterActivity parameter from AddTags method

d2d72e3

The parameter was only used for DisplayName setting which was removed as redundant. Co-authored-by: stephentoub <[email protected]>

Copilot finished work on behalf of stephentoub January 12, 2026 23:10

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tarekgh approved these changes Jan 13, 2026

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stephentoub enabled auto-merge (squash) January 14, 2026 01:57

jeffhandley approved these changes Jan 14, 2026

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stephentoub merged commit d52a7b1 into main Jan 14, 2026
20 of 24 checks passed

stephentoub deleted the copilot/implement-standard-convention-mcp branch January 14, 2026 02:07

Align telemetry with OpenTelemetry MCP semantic conventions #1139

Align telemetry with OpenTelemetry MCP semantic conventions #1139

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