fix: align MCP span naming and metric buckets with OTel MCP semantic conventions#268
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adityamehra merged 3 commits intomainfrom Apr 16, 2026
Merged
fix: align MCP span naming and metric buckets with OTel MCP semantic conventions#268adityamehra merged 3 commits intomainfrom
adityamehra merged 3 commits intomainfrom
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…conventions
MCPToolCall spans now use {mcp.method.name} {tool_name} format (e.g.
"tools/call add") with CLIENT/SERVER SpanKind, matching the OTel MCP
semconv spec. Previously used "execute_tool {tool_name}" with INTERNAL.
Added explicit bucket boundaries [0.01..300] to all MCP duration
histograms per semconv specification.
Made-with: Cursor
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etserend
approved these changes
Apr 15, 2026
shuningc
reviewed
Apr 15, 2026
| @@ -783,8 +784,14 @@ def _start_tool_call(self, tool: ToolCall) -> None: | |||
| Span name: execute_tool {gen_ai.tool.name} | |||
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It could be clearer to mention this span name only applies to non MCP tool calls
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Pls see below lines for the comment -
MCPToolCall instances are dispatched to _start_mcp_tool_call for
MCP semconv span naming ({mcp.method.name} {target}) and SpanKind.
wrisa
approved these changes
Apr 15, 2026
| """ | ||
| # Span name per semconv: "execute_tool {gen_ai.tool.name}" | ||
| if isinstance(tool, MCPToolCall): | ||
| self._start_mcp_tool_call(tool) |
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Why duplicate logic for span creation in this method ? Can we just have separate logic for name and kind here for mcp tools?
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Forgot to explicitly mention it to the coding agent to follow DRY. I will clean it in the next PR
Resolve conflict in instruments.py: keep both MCP operation duration buckets (from this branch) and evaluation cost buckets (from main). Made-with: Cursor
…naming Made-with: Cursor # Conflicts: # util/opentelemetry-util-genai/src/opentelemetry/util/genai/instruments.py
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Summary
MCPToolCallspans now use{mcp.method.name} {tool_name}format (e.g.tools/call add) instead ofexecute_tool {tool_name}, matching the OTel MCP semantic conventionsCLIENTfor client-side,SERVERfor server-side (wasINTERNAL)[0.01, 0.02, 0.05, 0.1, 0.2, 0.5, 1, 2, 5, 10, 30, 60, 120, 300]Sample span output
From
dev_assistant_client.py --console(client-sidecall_toolspan):{ "name": "tools/call get_system_info", "kind": "SpanKind.CLIENT", "parent_id": "0x9b8290b6d8c0f51b", "status": { "status_code": "UNSET" }, "attributes": { "gen_ai.operation.name": "execute_tool", "gen_ai.provider.name": "mcp", "gen_ai.agent.name": "mcp.client", "gen_ai.tool.name": "get_system_info", "gen_ai.tool.call.id": "312fadba-c1b5-46e5-b984-10440d7ffd6f", "gen_ai.tool.type": "extension", "mcp.method.name": "tools/call", "network.transport": "pipe" } }Before (old span naming):
After (MCP semconv aligned):
Test plan
make lintpasses (no new issues in changed files)pytest util/opentelemetry-util-genai/tests/-- 181 passedpytest instrumentation-genai/opentelemetry-instrumentation-fastmcp/tests/-- 74 passeddev_assistant_client.py --consolesmoke test confirmstools/call {name}spans withSpanKind.CLIENTexecute_tool {name}/INTERNAL)