Cloudflare Agents SDK

# Cloudflare Agents SDK

Your knowledge of the Agents SDK may be outdated. Prefer retrieval over pre-training for any Agents SDK task.

Retrieval Sources

Fetch current docs from `https://github.com/cloudflare/agents/tree/main/docs` before implementing.

| Topic | Doc | Use for | |-------|-----|---------| | Getting started | `docs/getting-started.md` | First agent, project setup | | State | `docs/state.md` | `setState`, `validateStateChange`, persistence | | Routing | `docs/routing.md` | URL patterns, `routeAgentRequest`, `basePath` | | Callable methods | `docs/callable-methods.md` | `@callable`, RPC, streaming, timeouts | | Scheduling | `docs/scheduling.md` | `schedule()`, `scheduleEvery()`, cron | | Workflows | `docs/workflows.md` | `AgentWorkflow`, durable multi-step tasks | | HTTP/WebSockets | `docs/http-websockets.md` | Lifecycle hooks, hibernation | | Email | `docs/email.md` | Email routing, secure reply resolver | | MCP client | `docs/mcp-client.md` | Connecting to MCP servers | | MCP server | `docs/mcp-servers.md` | Building MCP servers with `McpAgent` | | Client SDK | `docs/client-sdk.md` | `useAgent`, `useAgentChat`, React hooks | | Human-in-the-loop | `docs/human-in-the-loop.md` | Approval flows, pausing workflows | | Resumable streaming | `docs/resumable-streaming.md` | Stream recovery on disconnect |

Cloudflare docs: https://developers.cloudflare.com/agents/

Capabilities

The Agents SDK provides:

• Persistent state - SQLite-backed, auto-synced to clients
• Callable RPC - `@callable()` methods invoked over WebSocket
• Scheduling - One-time, recurring (`scheduleEvery`), and cron tasks
• Workflows - Durable multi-step background processing via `AgentWorkflow`
• MCP integration - Connect to MCP servers or build your own with `McpAgent`
• Email handling - Receive and reply to emails with secure routing
• Streaming chat - `AIChatAgent` with resumable streams
• React hooks - `useAgent`, `useAgentChat` for client apps

FIRST: Verify Installation

```bash npm ls agents # Should show agents package ```

If not installed: ```bash npm install agents ```

Wrangler Configuration

```jsonc { "durable_objects": { "bindings": [{ "name": "MyAgent", "class_name": "MyAgent" }] }, "migrations": [{ "tag": "v1", "new_sqlite_classes": ["MyAgent"] }] } ```

Agent Class

```typescript import { Agent, routeAgentRequest, callable } from "agents";

type State = { count: number };

export class Counter extends Agent<Env, State> { initialState = { count: 0 };

// Validation hook - runs before state persists (sync, throwing rejects the update) validateStateChange(nextState: State, source: Connection | "server") { if (nextState.count < 0) throw new Error("Count cannot be negative"); }

// Notification hook - runs after state persists (async, non-blocking) onStateUpdate(state: State, source: Connection | "server") { console.log("State updated:", state); }

@callable() increment() { this.setState({ count: this.state.count + 1 }); return this.state.count; } }

export default { fetch: (req, env) => routeAgentRequest(req, env) ?? new Response("Not found", { status: 404 }) }; ```

Routing

Requests route to `/agents/{agent-name}/{instance-name}`:

| Class | URL | |-------|-----| | `Counter` | `/agents/counter/user-123` | | `ChatRoom` | `/agents/chat-room/lobby` |

Client: `useAgent({ agent: "Counter", name: "user-123" })`

Core APIs

| Task | API | |------|-----| | Read state | `this.state.count` | | Write state | `this.setState({ count: 1 })` | | SQL query | `` this.sql`SELECT * FROM users WHERE id = ${id}` `` | | Schedule (delay) | `await this.schedule(60, "task", payload)` | | Schedule (cron) | `await this.schedule("0 * * * *", "task", payload)` | | Schedule (interval) | `await this.scheduleEvery(30, "poll")` | | RPC method | `@callable() myMethod() { ... }` | | Streaming RPC | `@callable({ streaming: true }) stream(res) { ... }` | | Start workflow | `await this.runWorkflow("ProcessingWorkflow", params)` |

React Client

```tsx import { useAgent } from "agents/react";

function App() { const [state, setLocalState] = useState({ count: 0 });

const agent = useAgent({ agent: "Counter", name: "my-instance", onStateUpdate: (newState) => setLocalState(newState), onIdentity: (name, agentType) => console.log(`Connected to ${name}`) });

return ( <button onClick={() => agent.setState({ count: state.count + 1 })}> Count: {state.count} </button> ); } ```

References

• references/workflows.md - Durable Workflows integration
• references/callable.md - RPC methods, streaming, timeouts
• references/state-scheduling.md - State persistence, scheduling
• references/streaming-chat.md - AIChatAgent, resumable streams
• references/mcp.md - MCP server integration
• references/email.md - Email routing and handling
• references/codemode.md - Code Mode (experimental)