Workers AI Function Calling types

I copied the "traditional" example at https://developers.cloudflare.com/workers-ai/function-calling/ into a worker like this:

export default {
    async fetch(request, env, ctx): Promise<Response> {
        const response = await env.AI.run(
            "@hf/nousresearch/hermes-2-pro-mistral-7b", {
                messages: [{
                    role: "user",
                    content: "Who is Cloudflare on github?"
                }],
                tools: [{
                    name: "getGithubUser",
                    description: "Provides publicly available information about someone with a GitHub account.",
                    parameters: {
                        type: "object",
                        properties: {
                            username: {
                                type: "string",
                                description: "The handle for the GitHub user account.",
                            },
                        },
                        required: ["username"],
                    },
                }, ],
            },
        );

        const selected_tool = response.tool_calls[0];
        let res;

        if (selected_tool.name == "getGithubUser") {
            try {
                const username = selected_tool.arguments.username;
                const url = `https://api.github.com/users/${username}`;
                res = await fetch(url, {
                    headers: {
                        // Github API requires a User-Agent header
                        "User-Agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/112.0.0.0 Safari/537.36",
                    },
                }).then((res) => res.json());
            } catch (error) {
                return error;
            }
        }

        const finalResponse = await env.AI.run(
            "@hf/nousresearch/hermes-2-pro-mistral-7b", {
                messages: [{
                        role: "user",
                        content: "Who is Cloudflare on github?",
                    },
                    {
                        role: "assistant",
                        content: "",
                        tool_call: selected_tool.name,
                    },
                    {
                        role: "tool",
                        name: selected_tool.name,
                        content: JSON.stringify(res),
                    },
                ],
                tools: [{
                    name: "getGithubUser",
                    description: "Provides publicly available information about someone with a GitHub account.",
                    parameters: {
                        type: "object",
                        properties: {
                            username: {
                                type: "string",
                                description: "The handle for the GitHub user account.",
                            },
                        },
                        required: ["username"],
                    },
                }, ],
            },
        );
        return new Response(JSON.stringify(finalResponse));
    },
} satisfies ExportedHandler<Env>;

where Env is:

interface Env {
    AI: Ai;
}

This resulted in the following TypeScript errors in VSCode and when I ran npx tsc --noEmit:

src/index.ts:4:4 - error TS2769: No overload matches this call.
  The last overload gave the following error.
    Argument of type '"@hf/nousresearch/hermes-2-pro-mistral-7b"' is not assignable to parameter of type 'BaseAiImageToTextModels'.

4    "@hf/nousresearch/hermes-2-pro-mistral-7b", {
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

  node_modules/@cloudflare/workers-types/experimental/index.d.ts:3718:3
    3718   run(
           ~~~
    The last overload is declared here.

src/index.ts:26:34 - error TS2339: Property 'tool_calls' does not exist on type '(((AiTextClassificationOutput & Uint8Array & (AiTextEmbeddingsOutput & AiSpeechRecognitionOutput & AiTextGenerationOutput)) & AiTranslationOutput) & AiSummarizationOutput) & AiImageToTextOutput'.
  Property 'tool_calls' does not exist on type 'AiTextClassificationOutput & Uint8Array & AiTextEmbeddingsOutput & AiSpeechRecognitionOutput & ReadableStream<...> & AiTranslationOutput & AiSummarizationOutput & AiImageToTextOutput'.

26   const selected_tool = response.tool_calls[0];
                                    ~~~~~~~~~~

src/index.ts:40:5 - error TS2322: Type 'unknown' is not assignable to type 'Response'.

40     return error;
       ~~~~~~

src/index.ts:45:4 - error TS2769: No overload matches this call.
  The last overload gave the following error.
    Argument of type '"@hf/nousresearch/hermes-2-pro-mistral-7b"' is not assignable to parameter of type 'BaseAiImageToTextModels'.

45    "@hf/nousresearch/hermes-2-pro-mistral-7b", {
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

  node_modules/@cloudflare/workers-types/experimental/index.d.ts:3718:3
    3718   run(
           ~~~
    The last overload is declared here.

Found 4 errors in the same file, starting at: src/index.ts:4

I suspect this is somewhat related to the function overloading DX issues as reported at https://github.com/cloudflare/workerd/issues/2181.

cloudflare / workerd

Workers AI Function Calling types #2418