Incorrect `args` format in `tool-call` messages when calling functions with no parameters

[zvictor]

Description

While porting gemini-chatbot to the Anthropic's provider, I faced an error regarding tool/function calling with no parameters.

Functions that have no parameters lead to tool-call messages in which "args": "" instead of "args": "{}".
Example:

{
  "type": "tool-call",
  "toolCallType": "function",
  "toolCallId": "toolu_01RFn8zb3tbVnyiJ2FjhPqxb",
  "toolName": "showHotels",
  "args": ""
}

AI SDK does not accept that, leading to a AI_JSONParseError: JSON parsing failed: Text: .:

ai/packages/core/core/generate-text/tool-call.ts

Lines 68 to 71 in 55a2368

	const parseResult = safeParseJSON({
	text: toolCall.args,
	schema: tool.parameters,
	});

Code example

Source definition of the showHotels function:

import { tool } from 'ai'

tool({
  description: 'Show the UI to choose a hotel for the trip.',
  parameters: z.object({})
})

The code is located at lib/chat/tools/showHotels.tsx:14, which is then imported at lib/chat/actions.tsx:220.

JSON definition of the showHotels function:

{
  "type": "function",
  "name": "showHotels",
  "description": "Show the UI to choose a hotel for the trip.",
  "parameters": {
    "type": "object",
    "properties": {},
    "additionalProperties": false,
    "$schema": "http://json-schema.org/draft-07/schema#"
  }
}

Tool call:

{
  "type": "tool-call",
  "toolCallType": "function",
  "toolCallId": "toolu_01RFn8zb3tbVnyiJ2FjhPqxb",
  "toolName": "showHotels",
  "args": ""
}

Parse error:

AI_JSONParseError: JSON parsing failed: Text: .
Error message: Unexpected end of JSON input
    at safeParseJSON (webpack-internal:///(rsc)/./node_modules/.pnpm/@ai-sdk+provider-utils@0.0.16_zod@3.23.8/node_modules/@ai-sdk/provider-utils/dist/index.mjs:271:109)
    at parseToolCall (webpack-internal:///(rsc)/./node_modules/.pnpm/ai@3.2.7_openai@4.52.0_react@18.3.1_solid-js@1.8.17_svelte@4.2.18_vue@3.4.30_typescript@5.5.2__zod@3.23.8/node_modules/ai/dist/index.mjs:1184:92)
    ...

Adicional context

If you change the parameters definition to something like z.object({ city: z.string() }, it works.

[lgrammel]

Can you provide the tool definition in typescript / AI SDK code?

The following example works for me:

import { anthropic } from '@ai-sdk/anthropic';
import { generateText, tool } from 'ai';
import dotenv from 'dotenv';
import { z } from 'zod';

dotenv.config();

async function main() {
  const result = await generateText({
    model: anthropic('claude-3-opus-20240229'),
    maxTokens: 512,
    tools: {
      showBerlinCityAttractions: tool({
        description: 'Show Berlin city attractions',
        parameters: z.object({}),
        execute: async () => {
          console.log('Showing city attractions');
        },
      }),
    },
    prompt: 'Show Berlin city attractions',
  });

  console.log(JSON.stringify(result, null, 2));
}

main().catch(console.error);

[zvictor]

Can you provide the tool definition in typescript / AI SDK code?

import { tool } from 'ai'

tool({
  description: 'Show the UI to choose a hotel for the trip.',
  parameters: z.object({})
})

It's located at lib/chat/tools/showHotels.tsx:14, which is then imported at lib/chat/actions.tsx:220.

If you change the parameters definition to something like z.object({ city: z.string() }, it works.

[zvictor]

The following example works for me

Yes, it works for me as well! But that's only when using generateText. If you go for streamText instead, it will throw the error:

Delta {"type":"error","error":{"name":"AI_InvalidToolArgumentsError","message":"Invalid arguments for tool showBerlinCityAttractions: JSON parsing failed: Text: .\nError message: Unexpected end of JSON input","cause":{"name":"AI_JSONParseError","message":"JSON parsing failed: Text: .\nError message: Unexpected end of JSON input","cause":{},"stack":"AI_JSONParseError: JSON parsing failed: Text: .\nError message: Unexpected end of JSON input\n    at safeParseJSON (file:///node_modules/.pnpm/@ai-sdk+provider-utils@0.0.16_zod@3.23.8/node_modules/@ai-sdk/provider-utils/dist/index.mjs:241:63)\n    at parseToolCall (file:///node_modules/.pnpm/ai@3.2.7_openai@4.52.0_react@18.3.1_solid-js@1.8.17_svelte@4.2.18_vue@3.4.30_typescript@5.5.2__zod@3.23.8/node_modules/ai/dist/index.mjs:1114:23)\n    at Object.transform (file:///node_modules/.pnpm/ai@3.2.7_openai@4.52.0_react@18.3.1_solid-js@1.8.17_svelte@4.2.18_vue@3.4.30_typescript@5.5.2__zod@3.23.8/node_modules/ai/dist/index.mjs:1313:30)\n    at invokePromiseCallback (node:internal/webstreams/util:180:10)\n    at Object.transformAlgorithm (node:internal/webstreams/util:185:23)\n    at transformStreamDefaultControllerPerformTransform (node:internal/webstreams/transformstream:526:37)\n    at transformStreamDefaultSinkWriteAlgorithm (node:internal/webstreams/transformstream:572:10)\n    at node:internal/webstreams/transformstream:377:16\n    at writableStreamDefaultControllerProcessWrite (node:internal/webstreams/writablestream:1127:5)\n    at writableStreamDefaultControllerAdvanceQueueIfNeeded (node:internal/webstreams/writablestream:1242:5)","valueText":""},"stack":"AI_InvalidToolArgumentsError: Invalid arguments for tool showBerlinCityAttractions: JSON parsing failed: Text: .\nError message: Unexpected end of JSON input\n    at parseToolCall (file:///node_modules/.pnpm/ai@3.2.7_openai@4.52.0_react@18.3.1_solid-js@1.8.17_svelte@4.2.18_vue@3.4.30_typescript@5.5.2__zod@3.23.8/node_modules/ai/dist/index.mjs:1119:11)\n    at Object.transform (file:///node_modules/.pnpm/ai@3.2.7_openai@4.52.0_react@18.3.1_solid-js@1.8.17_svelte@4.2.18_vue@3.4.30_typescript@5.5.2__zod@3.23.8/node_modules/ai/dist/index.mjs:1313:30)\n    at invokePromiseCallback (node:internal/webstreams/util:180:10)\n    at Object.transformAlgorithm (node:internal/webstreams/util:185:23)\n    at transformStreamDefaultControllerPerformTransform (node:internal/webstreams/transformstream:526:37)\n    at transformStreamDefaultSinkWriteAlgorithm (node:internal/webstreams/transformstream:572:10)\n    at node:internal/webstreams/transformstream:377:16\n    at writableStreamDefaultControllerProcessWrite (node:internal/webstreams/writablestream:1127:5)\n    at writableStreamDefaultControllerAdvanceQueueIfNeeded (node:internal/webstreams/writablestream:1242:5)\n    at writableStreamDefaultControllerWrite (node:internal/webstreams/writablestream:1116:3)","toolName":"showBerlinCityAttractions","toolArgs":""}}
Delta {"type":"finish","finishReason":"tool-calls","usage":{"promptTokens":346,"completionTokens":42,"totalTokens":388}}

Try this:

import { anthropic } from '@ai-sdk/anthropic'
import { streamText, tool } from 'ai'
import dotenv from 'dotenv'
import { z } from 'zod'

dotenv.config()

async function main() {
  const result = await streamText({
    model: anthropic('claude-3-haiku-20240307'),
    maxTokens: 512,
    tools: {
      showBerlinCityAttractions: tool({
        description: 'Show Berlin city attractions',
        parameters: z.object({}),
        execute: async () => {
          console.log('Showing city attractions')
        }
      })
    },
    prompt: 'Show Berlin city attractions'
  })

  for await (const delta of result.fullStream) {
    console.log(`Delta`, JSON.stringify(delta))
  }
}

main().catch(console.error)

[Legit4K]

bumping this as I'm also experiencing an error when I try to use an empty object via zod for a tool's parameters. when I define a parameter for the tool, everything works as expected.

URL type parameters are also no longer working:

Additional Context

I'm using the Google Generative API provider and I haven't made any changes over the past 2 days. Everything was stable until earlier today for me. Btw - i'm using generateText

[mnalley95]

bumping this as I'm also experiencing an error when I try to use an empty object via zod for a tool's parameters. when I define a parameter for the tool, everything works as expected.

URL type parameters are also no longer working:

Additional Context

I'm using the Google Generative API provider and I haven't made any changes over the past 2 days. Everything was stable until earlier today for me. Btw - i'm using generateText

Getting exact same error as you using GoogleGenerativeAI, url type, and streamText. Was also working fine 2-3 days ago, then am getting the exact same error today.

[sumitr3]

are you able to fix it?

[lgrammel]

#3073

[VaggelisKa]

I am facing the same issue when using the streamUI function. Was the same fix applied there as well? @lgrammel