Build a Custom Tool

import type { ToolDefinition } from '@allternit/sdk/ai-runtime/tools';

const weatherTool: ToolDefinition = {
  name: 'weather',
  description: 'Get the current weather for a city',
  input_schema: {
    type: 'object',
    properties: {
      city: { type: 'string', description: 'City name' },
      units: { type: 'string', enum: ['metric', 'imperial'] }
    },
    required: ['city']
  },
  execute: async (args: { city: string; units?: string }) => {
    const { city, units = 'metric' } = args;
    return { city, temperature: 22, units, condition: 'sunny' };
  }
};

import { ToolRegistry } from '@allternit/sdk/ai-runtime/tools';

const registry = new ToolRegistry();
registry.registerTool(weatherTool, { namespace: 'demo', strict: true });

console.log(registry.getTool('demo.weather'));

const valid = registry.validateInput('demo.weather', { city: 'Austin', units: 'imperial' });
console.log(valid.valid); // => true

const invalid = registry.validateInput('demo.weather', { city: 'Austin', timezone: 'CDT' });
console.log(invalid.errors); // => ["$.timezone is not allowed"]

const tool = registry.getTool('demo.weather')!;
const result = await tool.execute!(
  { city: 'Austin', units: 'imperial' },
  { callId: 'weather-1' }
);
// => { city: 'Austin', temperature: 22, units: 'imperial', condition: 'sunny' }

registry.registerDeferredTool({
  id: 'db-tool',
  name: 'query_db',
  description: 'Run a read-only SQL query',
  input_schema: {
    type: 'object',
    properties: { query: { type: 'string' } },
    required: ['query']
  },
  tags: ['database', 'sql']
});

const belt = new NativeToolBelt(registry);
await belt.attachMcpServer({
  serverId: 'demo',
  listTools: async () => [{
    name: 'weather',
    description: weatherTool.description,
    inputSchema: weatherTool.input_schema
  }],
  callTool: async (name, args) => {
    if (name !== 'weather') throw new Error('Unknown tool');
    return weatherTool.execute!(args, { callId: 'mcp-weather' });
  }
});

const snapshot = registry.snapshot();
const restored = new ToolRegistry();
restored.rehydrate(snapshot);