AI embedded functions calls - how can my function influence the AI response?

import { runWithTools } from '@cloudflare/ai-utils';
router.get('/ai', async (req, env) => {
    const fruit = ({fruit}) => {
        console.log(fruit);
        switch(fruit) {
            case 'orange': return '*******';
        }
    };
    return await runWithTools(
        env.AI,
        '@hf/nousresearch/hermes-2-pro-mistral-7b',
        {
            messages: [
                {
                    role: 'user',
                    content: 'Discern the following fruit: shares its name with a colour, is juicy, and is citrus.',
                },
            ],
            tools: [
                {
                    name: 'fruit',
                    description: `Output the user's favourite fruit`,
                    parameters: {
                        type: 'object',
                        properties: {
                            fruit: { type: 'fruit', description: `the user's favourite fruit` },
                        },
                        required: ['fruit'],
                    },
                    function: fruit,
                },
            ],
        }
    );
});