Structured output

Author: pietrozullo

examples/structured_output.ts

@@ -0,0 +1,110 @@
+/**
+ * Structured Output Example - City Research with Playwright
+ *
+ * This example demonstrates intelligent structured output by researching Padova, Italy.
+ * The agent becomes schema-aware and will intelligently retry to gather missing 
+ * information until all required fields can be populated.
+ */
+
+import { ChatOpenAI } from '@langchain/openai'
+import { config } from 'dotenv'
+import { z } from 'zod'
+import { MCPAgent, MCPClient } from '../index.js'
+
+// Load environment variables from .env file
+config()
+
+// Define the structured output schema using Zod
+const CityInfoSchema = z.object({
+  name: z.string().describe('Official name of the city'),
+  country: z.string().describe('Country where the city is located'),
+  region: z.string().describe('Region or state within the country'),
+  population: z.number().describe('Current population count'),
+  area_km2: z.number().describe('Area in square kilometers'),
+  foundation_date: z.string().describe('When the city was founded (approximate year or period)'),
+  mayor: z.string().describe('Current mayor or city leader'),
+  famous_landmarks: z.array(z.string()).describe('List of famous landmarks, monuments, or attractions'),
+  universities: z.array(z.string()).describe('List of major universities or educational institutions'),
+  economy_sectors: z.array(z.string()).describe('Main economic sectors or industries'),
+  sister_cities: z.array(z.string()).describe('Twin cities or sister cities partnerships'),
+  historical_significance: z.string().describe('Brief description of historical importance'),
+  climate_type: z.string().nullable().describe('Type of climate (e.g., Mediterranean, Continental)'),
+  elevation_meters: z.number().nullable().describe('Elevation above sea level in meters'),
+})
+
+type CityInfo = z.infer<typeof CityInfoSchema>
+
+async function main() {
+  const mcpConfig = {
+    mcpServers: {
+      playwright: {
+        command: 'npx',
+        args: ['@playwright/mcp@latest'],
+        env: {
+          DISPLAY: ':1',
+        },
+      },
+    },
+  }
+
+  const client = new MCPClient(mcpConfig)
+  const llm = new ChatOpenAI({ model: 'gpt-4o' })
+  const agent = new MCPAgent({ llm, client, maxSteps: 50, memoryEnabled: true })
+
+  try {
+    // Use structured output with intelligent retry
+    // The agent will:
+    // 1. Know exactly what information it needs to collect
+    // 2. Attempt structured output at finish points
+    // 3. Continue execution if required information is missing
+    // 4. Only finish when all required fields can be populated
+    const result: CityInfo = await agent.run(
+      `
+      Research comprehensive information about the city of Padova (also known as Padua) in Italy.
+      
+      Visit multiple reliable sources like Wikipedia, official city websites, tourism sites,
+      and university websites to gather detailed information including demographics, history,
+      governance, education, economy, landmarks, and international relationships.
+      `,
+      50,    // maxSteps
+      true,  // manageConnector 
+      [],    // externalHistory
+      CityInfoSchema  // outputSchema - this enables structured output
+    )
+
+    // Now you have strongly-typed, validated data!
+    console.log(`Name: ${result.name}`)
+    console.log(`Country: ${result.country}`)
+    console.log(`Region: ${result.region}`)
+    console.log(`Population: ${result.population.toLocaleString()}`)
+    console.log(`Area: ${result.area_km2} km²`)
+    console.log(`Foundation: ${result.foundation_date}`)
+    console.log(`Mayor: ${result.mayor}`)
+    console.log(`Universities: ${result.universities.join(', ')}`)
+    console.log(`Economy: ${result.economy_sectors.join(', ')}`)
+    console.log(`Landmarks: ${result.famous_landmarks.join(', ')}`)
+    console.log(`Sister Cities: ${result.sister_cities.length > 0 ? result.sister_cities.join(', ') : 'None'}`)
+    console.log(`Historical Significance: ${result.historical_significance}`)
+    
+    if (result.climate_type) {
+      console.log(`Climate: ${result.climate_type}`)
+    }
+    
+    if (result.elevation_meters !== null) {
+      console.log(`Elevation: ${result.elevation_meters} meters`)
+    }
+
+  } catch (error) {
+    console.error('Error:', error)
+  } finally {
+    await agent.close()
+  }
+}
+
+// Handle unhandled promise rejections
+process.on('unhandledRejection', (reason, promise) => {
+  console.error('Unhandled Rejection at:', promise, 'reason:', reason)
+  process.exit(1)
+})
+
+main().catch(console.error)

package.json

@@ -73,7 +73,8 @@
     "example:sandbox": "npm run build && node dist/examples/sandbox_everything.js",
     "example:oauth": "npm run build && node dist/examples/simple_oauth_example.js",
     "example:blender": "npm run build && node dist/examples/blender_use.js",
-    "example:add_server": "npm run build && node dist/examples/add_server_tool.js"
+    "example:add_server": "npm run build && node dist/examples/add_server_tool.js",
+    "example:structured": "npm run build && node dist/examples/structured_output.js"
   },
   "dependencies": {
     "@dmitryrechkin/json-schema-to-zod": "^1.0.1",