Components as Tools
Let your agent render rich React components directly in the chat by calling them as tools.
"""AG2 agent with weather and sales tools for CopilotKit showcase.Uses AG2's ConversableAgent with AGUIStream to exposethe agent via the AG-UI protocol."""from __future__ import annotationsimport jsonimport loggingfrom typing import Annotated, Anyimport openaifrom autogen import ConversableAgent, LLMConfigfrom autogen.ag_ui import AGUIStreamfrom dotenv import load_dotenvfrom pydantic import ValidationErrorload_dotenv()# Import shared tool implementationsfrom tools import ( get_weather_impl, query_data_impl, manage_sales_todos_impl, get_sales_todos_impl, schedule_meeting_impl, search_flights_impl, build_a2ui_operations_from_tool_call, RENDER_A2UI_TOOL_SCHEMA,)from tools.types import Flightfrom ._header_forwarding import get_forwarded_headersfrom ._request_context import get_latest_user_messagelogger = logging.getLogger(__name__)# Module-level async client: re-used across requests (httpx connection pool is# thread-safe). Using AsyncOpenAI inside an `async def` avoids blocking the# ASGI event loop on the secondary LLM call._async_openai_client = openai.AsyncOpenAI()# =====# Tools# =====async def get_weather( location: Annotated[str, "City name to get weather for"],) -> str: """Get current weather for a location.""" result = get_weather_impl(location) # Return a JSON string (not a dict): autogen serializes dict returns with # str(), producing a Python repr (single quotes) that the frontend's # parseJsonResult/JSON.parse cannot parse — the weather card then renders # "--" placeholders. Same pattern as search_flights below. return json.dumps( { "city": result["city"], "temperature": result["temperature"], "feels_like": result["feels_like"], "humidity": result["humidity"], "wind_speed": result["wind_speed"], "conditions": result["conditions"], } )async def query_data( query: Annotated[str, "Natural language query for financial data"],) -> str: """Query financial database for chart data.""" # Return a JSON string (not a list): autogen serializes non-str returns # with str(), producing a Python repr (single quotes) that the frontend's # parseJsonResult/JSON.parse cannot parse. Same pattern as get_weather. return json.dumps(query_data_impl(query))async def manage_sales_todos( todos: Annotated[list, "Complete list of sales todos"],) -> str: """Manage the sales pipeline.""" # See contract comment on query_data above — return JSON, not dict. # SalesTodo is a Pydantic model; coerce via model_dump for serialisability. result = [t.model_dump() for t in manage_sales_todos_impl(todos)] return json.dumps({"todos": result})async def get_sales_todos() -> str: """Get the current sales pipeline.""" # See contract comment on query_data above — return JSON, not list. # SalesTodo is a Pydantic model; coerce via model_dump for serialisability. return json.dumps([t.model_dump() for t in get_sales_todos_impl(None)])async def schedule_meeting( reason: Annotated[str, "Reason for the meeting"],) -> str: """Schedule a meeting with user approval.""" # See contract comment on query_data above — return JSON, not dict. return json.dumps(schedule_meeting_impl(reason))async def search_flights( flights: Annotated[ list[dict[str, Any]], "List of flight objects to display as rich A2UI cards" ],) -> str: """Search for flights and display the results as rich cards. Return exactly 2 flights. Each flight must have: airline, airlineLogo, flightNumber, origin, destination, date (short readable format like "Tue, Mar 18" -- use near-future dates), departureTime, arrivalTime, duration (e.g. "4h 25m"), status (e.g. "On Time" or "Delayed"), statusColor (hex color for status dot), price (e.g. "$289"), and currency (e.g. "USD"). For airlineLogo use Google favicon API: https://www.google.com/s2/favicons?domain={airline_domain}&sz=128 """ try: typed_flights: list[Flight] = [Flight(**f) for f in flights] except ValidationError as exc: logger.warning( "search_flights: invalid flight shape type=%s err=%s", type(exc).__name__, exc, exc_info=True, ) return json.dumps({"error": f"invalid flight shape: {exc}"}) result = search_flights_impl(typed_flights) return json.dumps(result)async def generate_a2ui( context: Annotated[str, "Conversation context to generate UI for"],) -> str: """Generate dynamic A2UI components based on the conversation. A secondary LLM designs the UI schema and data. The result is returned as an a2ui_operations container for the middleware to detect. """ # A13: AsyncOpenAI inside async def (was sync openai.OpenAI which blocks # the ASGI event loop). Forward x-* headers via extra_headers in addition # to the global httpx hook so aimock context routing is explicit at the # call site. # # R2-A1 / A4: thread the latest user prompt from the inbound # RunAgentInput.messages payload (captured into a per-request ContextVar # by RequestUserMessageMiddleware — see agents/_request_context.py) into # the inner LLM call so each pill's request body is byte-distinct. # Without this, every pill landing on the omnibus agent (agentic-chat / # tool-rendering / chat-customization-css / hitl) produces an IDENTICAL # inner-LLM body and the aimock fixture cannot disambiguate. Falls back # to the original hardcoded prompt when the middleware captured nothing # (parse failure already logged at WARNING). user_prompt = get_latest_user_message() or ( "Generate a dynamic A2UI dashboard based on the conversation." ) forwarded = get_forwarded_headers() try: response = await _async_openai_client.chat.completions.create( model="gpt-4.1", messages=[ { "role": "system", "content": context or "Generate a useful dashboard UI.", }, { "role": "user", "content": user_prompt, }, ], tools=[ { "type": "function", "function": RENDER_A2UI_TOOL_SCHEMA, } ], tool_choice={"type": "function", "function": {"name": "render_a2ui"}}, extra_headers=forwarded or None, ) except Exception as exc: logger.error( "generate_a2ui: inner LLM call failed type=%s err=%s", type(exc).__name__, exc, exc_info=True, ) return json.dumps({"error": f"inner LLM call failed: {type(exc).__name__}"}) if not response.choices: logger.warning("generate_a2ui: LLM returned no choices") return json.dumps({"error": "LLM returned no choices"}) choice = response.choices[0] if not choice.message.tool_calls: logger.warning("generate_a2ui: secondary LLM produced no render_a2ui tool call") return json.dumps({"error": "LLM did not call render_a2ui"}) try: args = json.loads(choice.message.tool_calls[0].function.arguments) result = build_a2ui_operations_from_tool_call(args) return json.dumps(result) except (json.JSONDecodeError, KeyError, TypeError, ValueError) as exc: logger.error( "generate_a2ui: failed to parse render_a2ui args type=%s err=%s", type(exc).__name__, exc, exc_info=True, ) return json.dumps( {"error": f"failed to parse render_a2ui args: {type(exc).__name__}"} )# =====# Agent# =====agent = ConversableAgent( name="assistant", system_message=( "You are a helpful sales assistant. You can look up current weather " "for any city using the get_weather tool, query financial data with " "query_data, manage the sales pipeline with manage_sales_todos and " "get_sales_todos, schedule meetings with schedule_meeting, search " "flights and display rich A2UI cards with search_flights, and " "generate dynamic A2UI dashboards with generate_a2ui. " "When asked about the weather, always use the tool rather than guessing. " "Be concise and friendly in your responses." ), llm_config=LLMConfig({"model": "gpt-4o-mini", "stream": True}), human_input_mode="NEVER", # Guard against infinite tool-call loops: AG2's ConversableAgent with # human_input_mode="NEVER" will keep executing tool calls indefinitely # if the LLM keeps requesting them. Without this limit the agent floods # Railway's log stream (500 logs/sec rate-limit), becomes unresponsive # to health probes, and gets killed by the watchdog. max_consecutive_auto_reply=15, functions=[ get_weather, query_data, manage_sales_todos, get_sales_todos, schedule_meeting, search_flights, generate_a2ui, ],)# AG-UI stream wrapperstream = AGUIStream(agent)What is this?#
Tool-based Generative UI is the simplest form of Generative UI: you register
a React component with useComponent, and CopilotKit exposes it to the
agent as a tool. When the agent calls the tool, CopilotKit renders your
component inline in the chat, passing the tool's arguments straight through
as typed props.
Unlike tool rendering, which wraps a real backend tool in a custom UI, tool-based GenUI is the component. There is no handler, no user interaction, no server-side execution. The agent decides when to show it, populates the data, and CopilotKit paints it.
When should I use this?#
Use useComponent when you want to:
- Display rich UI (cards, charts, tables, dashboards) inline in the chat
- Show structured data the agent has derived from its reasoning
- Render previews, status indicators, or visual summaries
- Let the agent present information beyond plain text
For components that need user interaction, see Human-in-the-loop. For operational transparency around a real backend tool, see Tool rendering.
How it works in code#
useComponent takes a name, a Zod schema for its props, and the component
to render. The runtime registers it as a frontend tool so the agent can
discover it, and Zod validates the LLM's arguments before they reach your
component.
useComponent({ name: "render_bar_chart", description: "Display a bar chart with labeled numeric values.", parameters: barChartPropsSchema, render: BarChart, });The component itself is ordinary React: it reads only its props and can stream in as the agent fills the payload. The example above uses Recharts for the bar chart; it doesn't know anything about CopilotKit.
The name you pass to useComponent is what the agent sees as the tool
name. Make it a verb like render_bar_chart or show_weather so the LLM
reliably picks it when the user asks for that visualization.