feat(claude-agent-sdk): capture gen_ai.skill.* on Skill load execute_tool span

Attach gen_ai.skill.name/id/description/version to the execute_tool span of
the built-in Skill tool. Telemetry is bound to the ToolUseBlock(name="Skill")
tool span (not the SKILL.md-injecting UserMessage TextBlock).

- skill.name from ToolUseBlock.input.skill (frontmatter.name fallback)
- skill.id = claude:project:<skill-name>
- skill.description/version read best-effort from <cwd>/.claude/skills/<name>/SKILL.md
  frontmatter (cwd from SystemMessage.data.cwd)
- fallback to UserMessage.tool_use_result.commandName when start info incomplete
- metadata read failures never propagate to the SDK call

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: sipercai

instrumentation-loongsuite/loongsuite-instrumentation-claude-agent-sdk/CHANGELOG.md

@@ -7,6 +7,15 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+### Added
+
+- Capture `gen_ai.skill.name`, `gen_ai.skill.id`, `gen_ai.skill.description`
+  and `gen_ai.skill.version` on the `execute_tool` span of the built-in
+  `Skill` tool. Skill metadata is read best-effort from the project-level
+  `SKILL.md` frontmatter (located via `SystemMessage.data.cwd`); `skill.id`
+  is reported as `claude:project:<skill-name>`. Metadata read failures never
+  affect the SDK call.
+
 ## Version 0.6.0 (2026-06-03)
 
 There are no changelog entries for this release.

instrumentation-loongsuite/loongsuite-instrumentation-claude-agent-sdk/src/opentelemetry/instrumentation/claude_agent_sdk/patch.py

@@ -15,9 +15,12 @@
 """Patch functions for Claude Agent SDK instrumentation."""
 
 import logging
+import os
 import time
 from typing import Any, Dict, List, Optional
 
+import yaml
+
 from opentelemetry import context as otel_context
 from opentelemetry.instrumentation.claude_agent_sdk.utils import (
     extract_usage_from_result_message,
@@ -86,6 +89,115 @@ def _clear_client_managed_runs() -> None:
     _client_managed_runs.clear()
 
 
+# The name of the Claude Agent SDK built-in tool that loads a Skill.
+_SKILL_TOOL_NAME = "Skill"
+
+# skill id prefix for project-scoped Claude Agent SDK skills.
+_SKILL_ID_PREFIX = "claude:project:"
+
+
+def _read_skill_metadata(skill_md_path: str) -> Dict[str, str]:
+    """Best-effort read of a Skill's SKILL.md frontmatter.
+
+    Returns a dict with any of ``name``/``description``/``version`` keys that
+    were present in the YAML frontmatter. On any error (missing file, parse
+    failure, ...) returns an empty dict so telemetry never breaks the SDK call.
+    """
+    try:
+        with open(skill_md_path, "r", encoding="utf-8") as f:
+            content = f.read()
+    except Exception:
+        # Missing or unreadable SKILL.md is expected for non-project skills.
+        return {}
+
+    return _parse_skill_frontmatter(content)
+
+
+def _parse_skill_frontmatter(content: str) -> Dict[str, str]:
+    """Parse the YAML frontmatter (``---`` delimited) of a SKILL.md body."""
+    try:
+        stripped = content.lstrip()
+        if not stripped.startswith("---"):
+            return {}
+        # Split off the leading ``---``; the next ``---`` closes the block.
+        after_open = stripped[3:]
+        end_index = after_open.find("\n---")
+        if end_index == -1:
+            # Frontmatter never closed; treat the remainder as the block.
+            frontmatter_text = after_open
+        else:
+            frontmatter_text = after_open[:end_index]
+
+        parsed = yaml.safe_load(frontmatter_text)
+        if not isinstance(parsed, dict):
+            return {}
+    except Exception:
+        return {}
+
+    metadata: Dict[str, str] = {}
+    for key in ("name", "description", "version"):
+        value = parsed.get(key)
+        if value is not None:
+            metadata[key] = str(value)
+    return metadata
+
+
+def _apply_skill_metadata(
+    tool_invocation: ExecuteToolInvocation,
+    skill_name: str,
+    cwd: Optional[str],
+) -> None:
+    """Attach ``gen_ai.skill.*`` attributes to a Skill load tool span.
+
+    Reads the project-level ``SKILL.md`` frontmatter best-effort and fills in
+    ``skill_name``/``skill_id``/``skill_description``/``skill_version`` on the
+    invocation. Any failure is swallowed so the SDK call is never affected.
+    """
+    if not skill_name:
+        return
+
+    metadata: Dict[str, str] = {}
+    if cwd:
+        skill_md_path = os.path.join(
+            cwd, ".claude", "skills", skill_name, "SKILL.md"
+        )
+        metadata = _read_skill_metadata(skill_md_path)
+
+    # gen_ai.skill.name: prefer frontmatter, fall back to the requested name.
+    name = metadata.get("name") or skill_name
+    tool_invocation.skill_name = name
+    tool_invocation.skill_id = f"{_SKILL_ID_PREFIX}{name}"
+
+    description = metadata.get("description")
+    if description:
+        tool_invocation.skill_description = description
+    version = metadata.get("version")
+    if version:
+        tool_invocation.skill_version = version
+
+
+def _apply_skill_fallback(
+    tool_invocation: ExecuteToolInvocation,
+    tool_use_result: Any,
+) -> None:
+    """Best-effort fallback to recover skill_name before closing a Skill span.
+
+    If ``skill_name`` was not captured at span start (e.g. cwd was unavailable
+    so SKILL.md could not be read), try ``UserMessage.tool_use_result.commandName``
+    per the SDK's Skill tool result format.
+    """
+    if tool_invocation.skill_name:
+        return
+    if not isinstance(tool_use_result, dict):
+        return
+    command_name = tool_use_result.get("commandName")
+    if command_name:
+        tool_invocation.skill_name = str(command_name)
+        tool_invocation.skill_id = (
+            f"{_SKILL_ID_PREFIX}{command_name}"
+        )
+
+
 def _extract_message_parts(msg: Any) -> List[Any]:
     """Extract parts (text + tool calls) from an AssistantMessage."""
     parts = []
@@ -113,12 +225,17 @@ def _create_tool_spans_from_message(
     agent_invocation: InvokeAgentInvocation,
     active_task_stack: List[Any],
     exclude_tool_names: Optional[List[str]] = None,
+    cwd: Optional[str] = None,
 ) -> None:
     """Create tool execution spans from ToolUseBlocks in an AssistantMessage.
 
     Tool spans are children of the active SubAgent span (if any), otherwise agent span.
     When a Task tool is created, it's pushed onto active_task_stack along with a SubAgent span.
 
+    For the built-in ``Skill`` tool, ``gen_ai.skill.*`` attributes are read
+    best-effort from the project-level ``SKILL.md`` frontmatter (located via
+    ``cwd``) and attached to the tool span.
+
     The stack structure is: [{"task": ExecuteToolInvocation, "subagent": InvokeAgentInvocation}, ...]
     """
     if not hasattr(msg, "content"):
@@ -163,6 +280,26 @@ def _create_tool_spans_from_message(
                     tool_call_arguments=tool_input,
                     tool_description=tool_name,
                 )
+
+                # Skill load: attach gen_ai.skill.* attributes best-effort
+                # from the project SKILL.md frontmatter. Failures here must
+                # never propagate to break the SDK call.
+                if tool_name == _SKILL_TOOL_NAME:
+                    try:
+                        skill_name = ""
+                        if isinstance(tool_input, dict):
+                            skill_name = str(
+                                tool_input.get("skill") or ""
+                            )
+                        _apply_skill_metadata(
+                            tool_invocation, skill_name, cwd
+                        )
+                    except Exception as e:
+                        logger.warning(
+                            f"Failed to read Skill metadata for "
+                            f"'{tool_input}': {e}"
+                        )
+
                 handler.start_execute_tool(tool_invocation)
                 _client_managed_runs[tool_use_id] = tool_invocation
 
@@ -271,6 +408,7 @@ def _process_assistant_message(
     handler: ExtendedTelemetryHandler,
     collected_messages: List[Dict[str, Any]],
     active_task_stack: List[Any],
+    cwd: Optional[str] = None,
 ) -> None:
     """Process AssistantMessage: create LLM turn, extract parts, create tool spans."""
     parts = _extract_message_parts(msg)
@@ -353,7 +491,7 @@ def _process_assistant_message(
         turn_tracker.close_llm_turn()
 
     _create_tool_spans_from_message(
-        msg, handler, agent_invocation, active_task_stack
+        msg, handler, agent_invocation, active_task_stack, cwd=cwd
     )
 
 
@@ -474,6 +612,18 @@ def _process_user_message(
                             Error(message=error_msg, type=RuntimeError),
                         )
                     else:
+                        # Skill load: best-effort fallback to fill skill_name
+                        # from the tool result if it wasn't captured at start.
+                        if tool_invocation.tool_name == _SKILL_TOOL_NAME:
+                            try:
+                                _apply_skill_fallback(
+                                    tool_invocation, tool_use_result
+                                )
+                            except Exception as e:
+                                logger.warning(
+                                    f"Failed to apply Skill metadata "
+                                    f"fallback: {e}"
+                                )
                         handler.stop_execute_tool(tool_invocation)
 
                 if tool_use_id:
@@ -522,18 +672,23 @@ def _process_user_message(
 def _process_system_message(
     msg: Any,
     agent_invocation: InvokeAgentInvocation,
-) -> None:
-    """Process SystemMessage: extract session_id early in the stream.
+) -> Optional[str]:
+    """Process SystemMessage: extract session_id and cwd early in the stream.
 
     SystemMessage appears at the beginning of the message stream and contains
-    the session_id in its data field. We extract it here so that it's available
-    for all subsequent LLM spans.
+    the session_id and cwd in its data field. We extract them here so they are
+    available for all subsequent spans (cwd is needed to locate project-level
+    SKILL.md files for Skill tool telemetry).
+
+    Returns the cwd if present, otherwise ``None``.
     """
     if hasattr(msg, "subtype") and msg.subtype == "init":
         if hasattr(msg, "data") and isinstance(msg.data, dict):
             session_id = msg.data.get("session_id")
             if session_id:
                 agent_invocation.conversation_id = session_id
+            return msg.data.get("cwd")
+    return None
 
 
 def _process_result_message(
@@ -590,12 +745,16 @@ async def _process_agent_invocation_stream(
     # When its ToolResultBlock is received, it's popped
     active_task_stack: List[Any] = []
 
+    # cwd captured from SystemMessage.data.cwd, used to locate project-level
+    # SKILL.md files for Skill tool telemetry.
+    session_cwd: Optional[str] = None
+
     try:
         async for msg in wrapped_stream:
             msg_type = type(msg).__name__
 
             if msg_type == "SystemMessage":
-                _process_system_message(msg, agent_invocation)
+                session_cwd = _process_system_message(msg, agent_invocation)
             elif msg_type == "AssistantMessage":
                 _process_assistant_message(
                     msg,
@@ -606,6 +765,7 @@ async def _process_agent_invocation_stream(
                     handler,
                     collected_messages,
                     active_task_stack,
+                    cwd=session_cwd,
                 )
             elif msg_type == "UserMessage":
                 _process_user_message(

instrumentation-loongsuite/loongsuite-instrumentation-claude-agent-sdk/tests/cassettes/test_skill_load.yaml

@@ -0,0 +1,76 @@
+description: 'Skill load: project-level probe-skill loaded via Skill tool'
+prompt: Use the probe-skill Skill tool first. Then answer exactly PROBE_SKILL_MARKER and nothing else.
+messages:
+- type: SystemMessage
+  subtype: init
+  data:
+    type: system
+    subtype: init
+    cwd: __SKILL_CWD__
+    session_id: skill-session-0001
+    tools:
+    - Skill
+    - Bash
+    - Read
+    skills:
+    - probe-skill
+    mcp_servers: []
+    model: qwen-plus
+    permissionMode: bypassPermissions
+    apiKeySource: ANTHROPIC_API_KEY
+    claude_code_version: 2.1.1
+    output_style: default
+    agents: []
+    slash_commands: []
+    plugins: []
+    uuid: skill-init-uuid
+- type: AssistantMessage
+  model: qwen-plus
+  content:
+  - type: ToolUseBlock
+    id: call_skill_load_probe
+    name: Skill
+    input:
+      skill: probe-skill
+  parent_tool_use_id: null
+  error: null
+- type: UserMessage
+  content:
+  - type: ToolResultBlock
+    tool_use_id: call_skill_load_probe
+    content: 'Launching skill: probe-skill'
+    is_error: false
+  uuid: skill-result-uuid
+  parent_tool_use_id: null
+  tool_use_result:
+    success: true
+    commandName: probe-skill
+- type: AssistantMessage
+  model: qwen-plus
+  content:
+  - type: TextBlock
+    text: PROBE_SKILL_MARKER
+  parent_tool_use_id: null
+  error: null
+- type: ResultMessage
+  subtype: success
+  duration_ms: 3210
+  duration_api_ms: 9000
+  is_error: false
+  num_turns: 2
+  session_id: skill-session-0001
+  total_cost_usd: 0.012
+  usage:
+    input_tokens: 1024
+    cache_creation_input_tokens: 0
+    cache_read_input_tokens: 0
+    output_tokens: 32
+    server_tool_use:
+      web_search_requests: 0
+      web_fetch_requests: 0
+    service_tier: standard
+    cache_creation:
+      ephemeral_1h_input_tokens: 0
+      ephemeral_5m_input_tokens: 0
+  result: PROBE_SKILL_MARKER
+  structured_output: null