Agents: surface tool failures without assistant output

src/agents/pi-embedded-runner/run.ts

@@ -431,6 +431,7 @@ export async function runEmbeddedPiAgent(
             assistantTexts: attempt.assistantTexts,
             toolMetas: attempt.toolMetas,
             lastAssistant: attempt.lastAssistant,
+            lastToolError: attempt.lastToolError,
             config: params.config,
             sessionKey: params.sessionKey ?? params.sessionId,
             verboseLevel: params.verboseLevel,

src/agents/pi-embedded-runner/run/attempt.ts

@@ -433,6 +433,7 @@ export async function runEmbeddedAttempt(
         getMessagingToolSentTexts,
         getMessagingToolSentTargets,
         didSendViaMessagingTool,
+        getLastToolError,
       } = subscription;
 
       const queueHandle: EmbeddedPiQueueHandle = {
@@ -665,6 +666,7 @@ export async function runEmbeddedAttempt(
         assistantTexts,
         toolMetas: toolMetasNormalized,
         lastAssistant,
+        lastToolError: getLastToolError?.(),
         didSendViaMessagingTool: didSendViaMessagingTool(),
         messagingToolSentTexts: getMessagingToolSentTexts(),
         messagingToolSentTargets: getMessagingToolSentTargets(),

src/agents/pi-embedded-runner/run/payloads.test.ts

@@ -111,4 +111,40 @@ describe("buildEmbeddedRunPayloads", () => {
     expect(payloads).toHaveLength(1);
     expect(payloads[0]?.text).toBe(errorJsonPretty.trim());
   });
+
+  it("adds a fallback error when a tool fails and no assistant output exists", () => {
+    const payloads = buildEmbeddedRunPayloads({
+      assistantTexts: [],
+      toolMetas: [],
+      lastAssistant: undefined,
+      lastToolError: { toolName: "browser", error: "tab not found" },
+      sessionKey: "session:telegram",
+      inlineToolResultsAllowed: false,
+      verboseLevel: "off",
+      reasoningLevel: "off",
+      toolResultFormat: "plain",
+    });
+
+    expect(payloads).toHaveLength(1);
+    expect(payloads[0]?.isError).toBe(true);
+    expect(payloads[0]?.text).toContain("browser");
+    expect(payloads[0]?.text).toContain("tab not found");
+  });
+
+  it("does not add tool error fallback when assistant output exists", () => {
+    const payloads = buildEmbeddedRunPayloads({
+      assistantTexts: ["All good"],
+      toolMetas: [],
+      lastAssistant: { stopReason: "end_turn" } as AssistantMessage,
+      lastToolError: { toolName: "browser", error: "tab not found" },
+      sessionKey: "session:telegram",
+      inlineToolResultsAllowed: false,
+      verboseLevel: "off",
+      reasoningLevel: "off",
+      toolResultFormat: "plain",
+    });
+
+    expect(payloads).toHaveLength(1);
+    expect(payloads[0]?.text).toBe("All good");
+  });
 });

src/agents/pi-embedded-runner/run/payloads.ts

@@ -23,6 +23,7 @@ export function buildEmbeddedRunPayloads(params: {
   assistantTexts: string[];
   toolMetas: ToolMetaEntry[];
   lastAssistant: AssistantMessage | undefined;
+  lastToolError?: { toolName: string; meta?: string; error?: string };
   config?: ClawdbotConfig;
   sessionKey: string;
   verboseLevel?: VerboseLevel;
@@ -155,6 +156,19 @@ export function buildEmbeddedRunPayloads(params: {
     });
   }
 
+  if (replyItems.length === 0 && params.lastToolError) {
+    const toolSummary = formatToolAggregate(
+      params.lastToolError.toolName,
+      params.lastToolError.meta ? [params.lastToolError.meta] : undefined,
+      { markdown: useMarkdown },
+    );
+    const errorSuffix = params.lastToolError.error ? `: ${params.lastToolError.error}` : "";
+    replyItems.push({
+      text: `⚠️ ${toolSummary} failed${errorSuffix}`,
+      isError: true,
+    });
+  }
+
   const hasAudioAsVoiceTag = replyItems.some((item) => item.audioAsVoice);
   return replyItems
     .map((item) => ({

src/agents/pi-embedded-runner/run/types.ts

@@ -74,6 +74,7 @@ export type EmbeddedRunAttemptResult = {
   assistantTexts: string[];
   toolMetas: Array<{ toolName: string; meta?: string }>;
   lastAssistant: AssistantMessage | undefined;
+  lastToolError?: { toolName: string; meta?: string; error?: string };
   didSendViaMessagingTool: boolean;
   messagingToolSentTexts: string[];
   messagingToolSentTargets: MessagingToolSend[];