Handle case of tool error to add to user message

Author: jahooma

packages/agent-runtime/src/__tests__/tool-validation-error.test.ts

@@ -59,7 +59,7 @@ describe('tool validation error handling', () => {
 
     const responseChunks: (string | PrintModeEvent)[] = []
 
-    await processStream({
+    const result = await processStream({
       ...agentRuntimeImpl,
       agentContext: {},
       agentState,
@@ -96,6 +96,9 @@ describe('tool validation error handling', () => {
     expect(errorEvents.length).toBe(1)
     expect(errorEvents[0].message).toContain('Invalid parameters for spawn_agents')
 
+    // Verify hadToolCallError is true so the agent loop continues
+    expect(result.hadToolCallError).toBe(true)
+
     // Verify NO tool_call event was emitted (since validation failed before that point)
     const toolCallEvents = responseChunks.filter(
       (chunk): chunk is Extract<PrintModeEvent, { type: 'tool_call' }> =>
@@ -125,6 +128,18 @@ describe('tool validation error handling', () => {
     expect(toolMessages.length).toBe(0)
     // And no assistant tool calls either
     expect(assistantToolCalls.length).toBe(0)
+
+    // Verify error message was added to message history for the LLM to see
+    const userMessages = agentState.messageHistory.filter(
+      (m) => m.role === 'user',
+    )
+    const errorUserMessage = userMessages.find((m) => {
+      const contentStr = Array.isArray(m.content)
+        ? m.content.map((p) => ('text' in p ? p.text : '')).join('')
+        : typeof m.content === 'string' ? m.content : ''
+      return contentStr.includes('Error during tool call') && contentStr.includes('Invalid parameters for spawn_agents')
+    })
+    expect(errorUserMessage).toBeDefined()
   })
 
   it('should still emit tool_call and tool_result for valid tool calls', async () => {

packages/agent-runtime/src/tools/stream-parser.ts

@@ -90,6 +90,8 @@ export async function processStream(
   const toolResultsToAddAfterStream: ToolMessage[] = []
   const toolCalls: (CodebuffToolCall | CustomToolCall)[] = []
   const assistantMessages: Message[] = []
+  let hadToolCallError = false
+  const errorMessages: Message[] = []
   const { promise: streamDonePromise, resolve: resolveStreamDonePromise } =
     Promise.withResolvers<void>()
   let previousToolCallFinished = streamDonePromise
@@ -120,6 +122,15 @@ export async function processStream(
             content: chunk.output,
           }
           assistantMessages.push(toolResultMessage)
+        } else if (chunk.type === 'error') {
+          hadToolCallError = true
+          errorMessages.push(
+            userMessage(
+              withSystemTags(
+                `Error during tool call: ${chunk.message}. Please check the tool name and arguments and try again.`,
+              ),
+            ),
+          )
         }
       }
       return onResponseChunk(chunk)
@@ -267,8 +278,6 @@ export async function processStream(
 
   // === STREAM CONSUMPTION LOOP ===
   let messageId: string | null = null
-  let hadToolCallError = false
-  const errorMessages: Message[] = []
 
   while (true) {
     if (signal.aborted) {