# Tool Invocation Missing Result Error

## Issue

When using `generateText()` or `streamText()`, you may encounter the error "ToolInvocation must have a result" when a tool without an `execute` function is called.

## Cause

The error occurs when you define a tool without an `execute` function and don't provide the result through other means (like `useChat`'s `onToolCall` or `addToolResult` functions).

Each time a tool is invoked, the model expects to receive a result before continuing the conversation. Without a result, the model cannot determine if the tool call succeeded or failed and the conversation state becomes invalid.

## Solution

You have two options for handling tool results:

1. Server-side execution using tools with an `execute` function:

```tsx
const tools = {
  weather: tool({
    description: 'Get the weather in a location',
    parameters: z.object({
      location: z
        .string()
        .describe('The city and state, e.g. "San Francisco, CA"'),
    }),
    execute: async ({ location }) => {
      // Fetch and return weather data
      return { temperature: 72, conditions: 'sunny', location };
    },
  }),
};
```

2. Client-side execution with `useChat` (omitting the `execute` function), but you must provide results in one of these ways:

```tsx
const { messages } = useChat({
  // Option 1: Handle using onToolCall
  onToolCall: async ({ toolCall }) => {
    if (toolCall.toolName === 'getLocation') {
      const result = await getLocationData();
      return result; // This becomes the tool result
    }
  },
});

}
```

```tsx
// Option 2: Use addToolResult (e.g. with interactive UI elements)
const { messages, addToolResult } = useChat();

// Inside your JSX, when rendering tool calls:
<button
  onClick={() =>
    addToolResult({
      toolCallId, // must provide tool call ID
      result: {
        /* your tool result */
      },
    })
  }
>
  Confirm
</button>;
```

<Note type="warning">
  Whether handling tools on the server or client, each tool call must have a
  corresponding result before the conversation can continue.
</Note>


## Navigation

- [Azure OpenAI Slow to Stream](/v4/docs/troubleshooting/azure-stream-slow)
- [Client-Side Function Calls Not Invoked](/v4/docs/troubleshooting/client-side-function-calls-not-invoked)
- [Server Actions in Client Components](/v4/docs/troubleshooting/server-actions-in-client-components)
- [useChat/useCompletion stream output contains 0:... instead of text](/v4/docs/troubleshooting/strange-stream-output)
- [Streamable UI Errors](/v4/docs/troubleshooting/streamable-ui-errors)
- [Tool Invocation Missing Result Error](/v4/docs/troubleshooting/tool-invocation-missing-result)
- [Streaming Not Working When Deployed](/v4/docs/troubleshooting/streaming-not-working-when-deployed)
- [Streaming Not Working When Proxied](/v4/docs/troubleshooting/streaming-not-working-when-proxied)
- [Getting Timeouts When Deploying on Vercel](/v4/docs/troubleshooting/timeout-on-vercel)
- [Unclosed Streams](/v4/docs/troubleshooting/unclosed-streams)
- [useChat Failed to Parse Stream](/v4/docs/troubleshooting/use-chat-failed-to-parse-stream)
- [Server Action Plain Objects Error](/v4/docs/troubleshooting/client-stream-error)
- [useChat No Response with maxSteps](/v4/docs/troubleshooting/use-chat-tools-no-response)
- [useChat "An error occurred"](/v4/docs/troubleshooting/use-chat-an-error-occurred)
- [streamText fails silently](/v4/docs/troubleshooting/stream-text-not-working)
- [NaN token counts when using streamText with OpenAI models](/v4/docs/troubleshooting/nan-token-counts-openai-streaming)
- [Model is not assignable to type "LanguageModelV1"](/v4/docs/troubleshooting/model-is-not-assignable-to-type)
- [TypeScript error "Cannot find namespace 'JSX'"](/v4/docs/troubleshooting/typescript-cannot-find-namespace-jsx)
- [React error "Maximum update depth exceeded"](/v4/docs/troubleshooting/react-maximum-update-depth-exceeded)
- [Jest: cannot find module 'ai/rsc'](/v4/docs/troubleshooting/jest-cannot-find-module-ai-rsc)
- [Schema must be JSON Schema of type object error](/v4/docs/troubleshooting/zod-v4-json-schema-type-error)


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