diff --git a/src/agents/subagent-announce-output.ts b/src/agents/subagent-announce-output.ts
index b40b105cfb2..02e13cb0cdd 100644
--- a/src/agents/subagent-announce-output.ts
+++ b/src/agents/subagent-announce-output.ts
@@ -58,6 +58,9 @@ export type AgentWaitResult = {
 export type SubagentRunOutcome = {
   status: "ok" | "error" | "timeout" | "unknown";
   error?: string;
+  startedAt?: number;
+  endedAt?: number;
+  elapsedMs?: number;
 };
 
 function extractToolResultText(content: unknown): string {
@@ -297,20 +300,30 @@ export function applySubagentWaitOutcome(params: {
     startedAt: params.startedAt,
     endedAt: params.endedAt,
   };
-  const waitError = typeof params.wait?.error === "string" ? params.wait.error : undefined;
-  if (params.wait?.status === "timeout") {
-    next.outcome = { status: "timeout" };
-  } else if (params.wait?.status === "error") {
-    next.outcome = { status: "error", error: waitError };
-  } else if (params.wait?.status === "ok") {
-    next.outcome = { status: "ok" };
-  }
   if (typeof params.wait?.startedAt === "number" && !next.startedAt) {
     next.startedAt = params.wait.startedAt;
   }
   if (typeof params.wait?.endedAt === "number" && !next.endedAt) {
     next.endedAt = params.wait.endedAt;
   }
+  const timing: Pick<SubagentRunOutcome, "startedAt" | "endedAt" | "elapsedMs"> = {};
+  if (typeof next.startedAt === "number") {
+    timing.startedAt = next.startedAt;
+  }
+  if (typeof next.endedAt === "number") {
+    timing.endedAt = next.endedAt;
+  }
+  if (typeof next.startedAt === "number" && typeof next.endedAt === "number") {
+    timing.elapsedMs = Math.max(0, next.endedAt - next.startedAt);
+  }
+  const waitError = typeof params.wait?.error === "string" ? params.wait.error : undefined;
+  if (params.wait?.status === "timeout") {
+    next.outcome = { status: "timeout", ...timing };
+  } else if (params.wait?.status === "error") {
+    next.outcome = { status: "error", error: waitError, ...timing };
+  } else if (params.wait?.status === "ok") {
+    next.outcome = { status: "ok", ...timing };
+  }
   return next;
 }
 
diff --git a/src/agents/tools/sessions-spawn-tool.ts b/src/agents/tools/sessions-spawn-tool.ts
index fa05597c721..4fcc0359cad 100644
--- a/src/agents/tools/sessions-spawn-tool.ts
+++ b/src/agents/tools/sessions-spawn-tool.ts
@@ -201,10 +201,13 @@ export function createSessionsSpawnTool(
           }>)
         : undefined;
 
+      const roleContext = requestedAgentId ? { role: requestedAgentId } : {};
+
       if (streamTo && runtime !== "acp") {
         return jsonResult({
           status: "error",
           error: `streamTo is only supported for runtime=acp; got runtime=${runtime}`,
+          ...roleContext,
         });
       }
 
@@ -212,6 +215,7 @@ export function createSessionsSpawnTool(
         return jsonResult({
           status: "error",
           error: `resumeSessionId is only supported for runtime=acp; got runtime=${runtime}`,
+          ...roleContext,
         });
       }
 
@@ -222,6 +226,7 @@ export function createSessionsSpawnTool(
             status: "error",
             error:
               "attachments are currently unsupported for runtime=acp; use runtime=subagent or remove attachments",
+            ...roleContext,
           });
         }
         const result = await spawnAcpDirect(
@@ -304,10 +309,15 @@ export function createSessionsSpawnTool(
               error: `Failed to register ACP run: ${summarizeError(err)}. Cleanup was attempted, but the already-started ACP run may still finish in the background.`,
               childSessionKey,
               runId: childRunId,
+              ...roleContext,
             });
           }
         }
-        return jsonResult(result);
+        return jsonResult(
+          result.status === "error" && requestedAgentId
+            ? { ...result, role: requestedAgentId }
+            : result,
+        );
       }
 
       const result = await spawnSubagentDirect(
@@ -345,7 +355,11 @@ export function createSessionsSpawnTool(
         },
       );
 
-      return jsonResult(result);
+      return jsonResult(
+        result.status === "error" && requestedAgentId
+          ? { ...result, role: requestedAgentId }
+          : result,
+      );
     },
   };
 }