fix(eval): ignore malformed telemetry tool names

Author: morluto

src/jacobian/eval/telemetry.py

@@ -213,7 +213,9 @@ def _mcp_resource_link_uris(item: Mapping[str, Any]) -> tuple[str, ...]:
 def _mcp_resource_read_uri(item: Mapping[str, Any]) -> str | None:
     item_type = item.get("type")
     tool = item.get("tool")
-    if item_type != "mcp_resource_read" and tool not in _RESOURCE_READ_TOOL_NAMES:
+    if item_type != "mcp_resource_read" and (
+        not isinstance(tool, str) or tool not in _RESOURCE_READ_TOOL_NAMES
+    ):
         return None
     for key in ("arguments", "params", "input"):
         value = item.get(key)

tests/unit/tooling/test_eval_telemetry.py

@@ -172,6 +172,24 @@ def test_agent_telemetry_ignores_non_string_mcp_status(tmp_path: Path) -> None:
     assert telemetry["mcp_resource_read_successes"] == 1
 
 
+def test_agent_telemetry_ignores_non_string_mcp_tool(tmp_path: Path) -> None:
+    event = {
+        "type": "item.completed",
+        "item": {
+            "type": "not_resource_read",
+            "tool": [],
+            "arguments": {"uri": "artifact://sha256/" + ("a" * 64)},
+        },
+    }
+    transcript = tmp_path / "transcript.jsonl"
+    transcript.write_text(json.dumps(event) + "\n", encoding="utf-8")
+
+    telemetry = parse_agent_transcript(transcript)
+
+    assert telemetry["mcp_calls"] == []
+    assert telemetry["mcp_resource_read_attempts"] == 0
+
+
 def test_agent_telemetry_reports_reasoning_protocol_without_summary_text(
     tmp_path: Path,
 ) -> None: