Signal · API

defineTool

defineTool defines a tool from a name, a description, a Zod schema for its input, and an execute function. Signal sends the model the name, the description and the input schema converted to JSON Schema (parameters); execute is never sent. The model’s reply is scripted and makes no tool call; no model is called.

Tool

defineTool({
  name: 'seatsLeft',
  description: 'How many seats are left on a night',
  input: z.object({ night: z.string().describe('The night, as YYYY-MM-DD') }),
  execute: ({ night }) => ({ night, left: seatsLeftOn(night) }),
})

Tools in the request

[
  {
    type: 'function',
    function: {
      name: 'seatsLeft',
      description: 'How many seats are left on a night',
      parameters: {
        $schema: 'http://json-schema.org/draft-07/schema#',
        type: 'object',
        properties: {
          night: {
            type: 'string',
            description: 'The night, as YYYY-MM-DD',
          },
        },
        required: ['night'],
        additionalProperties: false,
      },
    },
  },
]

Output matches the expected value

Runs in this page on the installed package. The input and the expected output are defined by the example.