diff --git a/hud/agents/misc/response_agent.py b/hud/agents/misc/response_agent.py
index 617db6a0..4142a624 100644
--- a/hud/agents/misc/response_agent.py
+++ b/hud/agents/misc/response_agent.py
@@ -6,6 +6,7 @@
 from openai import AsyncOpenAI
 
 from hud.settings import settings
+from hud.telemetry import instrument
 
 logger = logging.getLogger(__name__)
 
@@ -64,6 +65,11 @@ def __init__(
         self.model = model
         self.system_prompt = system_prompt or DEFAULT_SYSTEM_PROMPT
 
+    @instrument(
+        category="agent",
+        name="response_agent",
+        internal_type="user-message",
+    )
     async def determine_response(self, agent_message: str) -> ResponseType:
         """
         Determine whether the agent should stop or continue based on its message.
@@ -86,6 +92,7 @@ async def determine_response(self, agent_message: str) -> ResponseType:
                 ],
                 temperature=0.1,
                 max_tokens=5,
+                extra_headers={"Trace-Id": ""},
             )
 
             response_text = response.choices[0].message.content
diff --git a/hud/eval/instrument.py b/hud/eval/instrument.py
index c2767f78..5d97cf87 100644
--- a/hud/eval/instrument.py
+++ b/hud/eval/instrument.py
@@ -69,7 +69,8 @@ def _httpx_request_hook(request: Any) -> None:
     headers = _get_trace_headers()
     if headers is not None:
         for key, value in headers.items():
-            request.headers[key] = value
+            if key.lower() not in {k.lower() for k in request.headers}:
+                request.headers[key] = value
         logger.debug("Added trace headers to request: %s", url_str)
 
     # Auto-inject API key if not present or invalid (prefer contextvar, fallback to settings)
@@ -149,7 +150,8 @@ async def on_request_start(
         trace_headers = _get_trace_headers()
         if trace_headers is not None:
             for key, value in trace_headers.items():
-                params.headers[key] = value
+                if key.lower() not in {k.lower() for k in params.headers}:
+                    params.headers[key] = value
             logger.debug("Added trace headers to aiohttp request: %s", url_str)
 
         api_key = _get_api_key()
diff --git a/hud/telemetry/instrument.py b/hud/telemetry/instrument.py
index 204f11bd..e5a8aba4 100644
--- a/hud/telemetry/instrument.py
+++ b/hud/telemetry/instrument.py
@@ -83,6 +83,7 @@ def instrument(
     name: str | None = None,
     category: str = "function",
     span_type: str | None = None,
+    internal_type: str | None = None,
     record_args: bool = True,
     record_result: bool = True,
 ) -> Callable[[Callable[..., Any]], Callable[..., Any]]: ...
@@ -95,6 +96,7 @@ def instrument(
     name: str | None = None,
     category: str = "function",
     span_type: str | None = None,
+    internal_type: str | None = None,
     record_args: bool = True,
     record_result: bool = True,
 ) -> Callable[P, R]: ...
@@ -107,6 +109,7 @@ def instrument(
     name: str | None = None,
     category: str = "function",
     span_type: str | None = None,
+    internal_type: str | None = None,
     record_args: bool = True,
     record_result: bool = True,
 ) -> Callable[P, Awaitable[R]]: ...
@@ -118,6 +121,7 @@ def instrument(
     name: str | None = None,
     category: str = "function",
     span_type: str | None = None,
+    internal_type: str | None = None,
     record_args: bool = True,
     record_result: bool = True,
 ) -> Callable[..., Any]:
@@ -130,6 +134,7 @@ def instrument(
         name: Custom span name (defaults to module.function)
         category: Span category (e.g., "agent", "tool", "function", "mcp")
         span_type: Alias for category (deprecated, use category instead)
+        internal_type: Internal span type (e.g., "user-message")
         record_args: Whether to record function arguments
         record_result: Whether to record function result
 
@@ -204,7 +209,7 @@ def _build_span(
 
             # Build span
             span_id = uuid.uuid4().hex[:16]
-            span = {
+            span: dict[str, Any] = {
                 "name": span_name,
                 "trace_id": _normalize_trace_id(task_run_id),
                 "span_id": span_id,
@@ -216,6 +221,8 @@ def _build_span(
                 "attributes": attributes.model_dump(mode="json", exclude_none=True),
                 "exceptions": [{"message": error}] if error else None,
             }
+            if internal_type:
+                span["internal_type"] = internal_type
             return span
 
         @functools.wraps(func)