Cloudflare Agents SDK 支持 MCP elicitation
Agents, Workers - Agents can respond to MCP elicitation requests
使用 Cloudflare Agents 的开发者注意：MCP elicitation 支持让你能处理服务器发起的用户输入请求，需在 onStart() 中配置处理器，否则服务器会走回退。建议升级 agents 包并实现对应模式。
Agents connected to Model Context Protocol (MCP) servers with addMcpServer can now handle elicitation ↗ requests.
Elicitation lets an MCP server request user input while it handles a tool call. Form mode collects structured, non-sensitive data. URL mode asks for consent before opening an out-of-band flow, such as third-party authorization or payment.
sequenceDiagram
participant User
participant Agent as Agent (MCP client)
participant Server as MCP server
participant Browser
Server->>Agent: elicitation/create
Agent->>User: Show server, reason, and input or URL
User->>Agent: Submit, open, decline, or cancel
Agent->>Browser: Open URL after consent (URL mode)
Agent->>Server: accept, decline, or cancel
Server-->>Agent: Optional URL completion notificationRegister a handler for each mode your Agent supports in onStart():
import { Agent } from "agents";
export class MyAgent extends Agent {
onStart() {
this.mcp.configureElicitationHandlers({
form: (request, serverId) => this.forwardToUser(request, serverId),
url: (request, serverId) => this.forwardToUser(request, serverId),
});
}
forwardToUser(request, serverId) {
// Show the request in your UI and resolve after the user responds.
throw new Error(
`Implement elicitation for ${serverId}: ${request.params.message}`,
);
}
}import { Agent } from "agents";
import type { ElicitRequest, ElicitResult } from "agents/mcp";
export class MyAgent extends Agent<Env> {
onStart() {
this.mcp.configureElicitationHandlers({
form: (request, serverId) => this.forwardToUser(request, serverId),
url: (request, serverId) => this.forwardToUser(request, serverId),
});
}
private forwardToUser(
request: ElicitRequest,
serverId: string,
): Promise<ElicitResult> {
// Show the request in your UI and resolve after the user responds.
throw new Error(
`Implement elicitation for ${serverId}: ${request.params.message}`,
);
}
}Connections advertise only the modes with configured handlers. An Agent without handlers advertises no elicitation capability, which lets the server use its fallback. The SDK stores the advertised modes with each MCP server registration so they survive Durable Object hibernation. Callback functions remain in memory and reattach when onStart() runs.
For implementation details and a browser forwarding pattern, refer to MCP client elicitation. The mcp-client ↗ and mcp-elicitation ↗ examples implement both sides.
Upgrade
To update to this release:
npmyarnpnpmbun
npm i agents@latestyarn add agents@latestpnpm add agents@latestbun add agents@latest更进一步：量化金融体系
看懂新闻只是起点——沿量化金融路径，把它变成能交付的工程能力