diff --git a/headroom/proxy/helpers.py b/headroom/proxy/helpers.py
index 29364ac0d..f62fcb527 100644
--- a/headroom/proxy/helpers.py
+++ b/headroom/proxy/helpers.py
@@ -60,6 +60,12 @@ from headroom.proxy.tool_injection_config import (
 from headroom.proxy.tool_injection_config import (
     get_tool_tracker_max_sessions as _get_tool_tracker_max_sessions,
 )
+from headroom.proxy.tool_injection_logging import (
+    ToolInjectionDecision,
+)
+from headroom.proxy.tool_injection_logging import (
+    log_tool_injection_decision as _log_tool_injection_decision,
+)
 from headroom.proxy.tool_injection_tracker import SessionToolTracker as _SessionToolTracker
 from headroom.proxy.tool_name_policy import extract_tool_name
 
@@ -1930,12 +1936,7 @@ def log_tool_injection_decision(
     *,
     provider: str,
     session_id: str | None,
-    decision: Literal[
-        "inject_first_time",
-        "inject_sticky_replay",
-        "skip",
-        "skip_disabled_via_env",
-    ],
+    decision: ToolInjectionDecision,
     tool_definition_bytes_count: int,
     request_id: str | None,
 ) -> None:
@@ -1947,14 +1948,13 @@ def log_tool_injection_decision(
     tool definition contents (might contain user-specific schemas) per
     constraint #11.
     """
-    logger.info(
-        "event=tool_injection_decision provider=%s session_id=%s "
-        "decision=%s tool_definition_bytes_count=%d request_id=%s",
-        provider,
-        session_id or "",
-        decision,
-        tool_definition_bytes_count,
-        request_id or "",
+    _log_tool_injection_decision(
+        logger=logger,
+        provider=provider,
+        session_id=session_id,
+        decision=decision,
+        tool_definition_bytes_count=tool_definition_bytes_count,
+        request_id=request_id,
     )
 
 
diff --git a/headroom/proxy/tool_injection_logging.py b/headroom/proxy/tool_injection_logging.py
new file mode 100644
index 000000000..b6e9baa1d
--- /dev/null
+++ b/headroom/proxy/tool_injection_logging.py
@@ -0,0 +1,35 @@
+"""Logging policy for proxy tool-injection decisions."""
+
+from __future__ import annotations
+
+import logging
+from typing import Literal
+
+ToolInjectionDecision = Literal[
+    "inject_first_time",
+    "inject_sticky_replay",
+    "skip",
+    "skip_disabled_via_env",
+]
+
+
+def log_tool_injection_decision(
+    *,
+    logger: logging.Logger,
+    provider: str,
+    session_id: str | None,
+    decision: ToolInjectionDecision,
+    tool_definition_bytes_count: int,
+    request_id: str | None,
+) -> None:
+    """Emit a cache-affecting tool-injection decision without tool contents."""
+
+    logger.info(
+        "event=tool_injection_decision provider=%s session_id=%s "
+        "decision=%s tool_definition_bytes_count=%d request_id=%s",
+        provider,
+        session_id or "",
+        decision,
+        tool_definition_bytes_count,
+        request_id or "",
+    )
diff --git a/tests/test_tool_injection_logging.py b/tests/test_tool_injection_logging.py
new file mode 100644
index 000000000..568d05c73
--- /dev/null
+++ b/tests/test_tool_injection_logging.py
@@ -0,0 +1,48 @@
+from __future__ import annotations
+
+import logging
+
+import pytest
+
+from headroom.proxy.helpers import log_tool_injection_decision as helper_log_tool_injection_decision
+from headroom.proxy.tool_injection_logging import log_tool_injection_decision
+
+
+def test_logs_tool_injection_decision_without_contents(caplog: pytest.LogCaptureFixture) -> None:
+    logger = logging.getLogger("headroom.proxy.test_tool_injection_logging")
+
+    with caplog.at_level(logging.INFO, logger=logger.name):
+        log_tool_injection_decision(
+            logger=logger,
+            provider="anthropic",
+            session_id="session-1",
+            decision="inject_sticky_replay",
+            tool_definition_bytes_count=123,
+            request_id="req-1",
+        )
+
+    assert len(caplog.records) == 1
+    message = caplog.records[0].getMessage()
+    assert "event=tool_injection_decision" in message
+    assert "provider=anthropic" in message
+    assert "session_id=session-1" in message
+    assert "decision=inject_sticky_replay" in message
+    assert "tool_definition_bytes_count=123" in message
+    assert "request_id=req-1" in message
+    assert "memory_save" not in message
+    assert "headroom_retrieve" not in message
+
+
+def test_helper_wrapper_uses_proxy_logger(caplog: pytest.LogCaptureFixture) -> None:
+    with caplog.at_level(logging.INFO, logger="headroom.proxy"):
+        helper_log_tool_injection_decision(
+            provider="openai",
+            session_id=None,
+            decision="skip",
+            tool_definition_bytes_count=0,
+            request_id=None,
+        )
+
+    assert len(caplog.records) == 1
+    assert caplog.records[0].name == "headroom.proxy"
+    assert "session_id= decision=skip" in caplog.records[0].getMessage()