infochanged

Agents, Workers - Agents can respond to MCP elicitation requests

Announced: 2026-07-13
Tags: Agents, Workers
Severity: info, set by reef/rss-rule-v1
Source: https://developers.cloudflare.com/changelog/post/2026-07-13-mcp-client-elicitation/

Agents connected to Model Context Protocol (MCP) servers with <a href="https://developers.cloudflare.com/agents/model-context-protocol/apis/client-api/"><code>addMcpServer</code></a> can now handle <a href="https://modelcontextprotocol.io/specification/2025-11-25/client/elicitation" target="_blank" rel="noopener">elicitation ↗︎</a> 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. <pre class="mermaid">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 notification </pre> Register a handler for each mode your Agent supports in <code>onStart()</code>: <div><div data-nb-tabs data-nb-sync-key="workersExamples" class><div class="relative flex border-b border-border" role="tablist" data-nb-tabs-list></div><div class="mt-3"><div role="tabpanel" data-nb-tabs-content data-nb-tab-label="JavaScript" class><figure class="nb-code-figure" data-nb-lang="js"><pre class="astro-code astro-code-themes github-light github-dark nb-shiki-c6xiwz" tabindex="0" data-language="js" data-nb-lang="js"><code>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}, ); } }</code></pre></figure></div><div role="tabpanel" data-nb-tabs-content data-nb-tab-label="TypeScript" class><figure class="nb-code-figure" data-nb-lang="ts"><pre class="astro-code astro-code-themes github-light github-dark nb-shiki-c6xiwz" tabindex="0" data-language="ts" data-nb-lang="ts"><code>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}, ); } }</code></pre></figure></div></div></div><script type="module" src="https://developers.cloudflare.com/home/runner/work/cloudflare-docs/cloudflare-docs/src/components/ui/tabs/Tabs.astro?astro&type=script&index=0&lang.ts"></script></div> 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 <code>onStart()</code> runs. For implementation details and a browser forwarding pattern, refer to <a href="https://developers.cloudflare.com/agents/model-context-protocol/apis/client-api/#elicitation">MCP client elicitation</a>. The <a href="https://github.com/cloudflare/agents/tree/main/examples/mcp-client" target="_blank" rel="noopener"><code>mcp-client</code> ↗︎</a> and <a href="https://github.com/cloudflare/agents/tree/main/examples/mcp-elicitation" target="_blank" rel="noopener"><code>mcp-elicitation</code> ↗︎</a> examples implement both sides. <div tabindex="-1" class="heading-wrapper level-h4"><h4 id="upgrade">Upgrade</h4><a class="anchor-link" href="#upgrade"><svg width="16" height="16" viewBox="0 0 24 24"><path fill="currentcolor" d="m12.11 15.39-3.88 3.88a2.52 2.52 0 0 1-3.5 0 2.47 2.47 0 0 1 0-3.5l3.88-3.88a1 1 0 0 0-1.42-1.42l-3.88 3.89a4.48 4.48 0 0 0 6.33 6.33l3.89-3.88a1 1 0 1 0-1.42-1.42Zm8.58-12.08a4.49 4.49 0 0 0-6.33 0l-3.89 3.88a1 1 0 0 0 1.42 1.42l3.88-3.88a2.52 2.52 0 0 1 3.5 0 2.47 2.47 0 0 1 0 3.5l-3.88 3.88a1 1 0 1 0 1.42 1.42l3.88-3.89a4.49 4.49 0 0 0 0-6.33ZM8.83 15.17a1 1 0 0 0 1.1.22 1 1 0 0 0 .32-.22l4.92-4.92a1 1 0 0 0-1.42-1.42l-4.92 4.92a1 1 0 0 0 0 1.42Z"></path></svg></a></div> To update to this release: <script> if (!customElements.get("nb-pm-restore")) { customElements.define( "nb-pm-restore", class extends HTMLElement { connectedCallback() { const card = this.closest("[data-nb-pm]"); if (!card) return; let saved; try { saved = sessionStorage.getItem("ui-pm-tab"); } catch { return; } if (!saved) return; const tabs = card.querySelectorAll("[data-nb-pm-tab]"); let idx = -1; tabs.forEach(function (t, i) { if (t.textContent.trim() === saved) idx = i; }); if (idx < 1) return; tabs.forEach(function (t, i) { t.setAttribute("aria-selected", String(i === idx)); }); card.querySelectorAll("[data-nb-pm-panel]").forEach(function (p, i) { p.hidden = i !== idx; }); } }, ); } </script><div data-nb-pm class="w-full"><div class="flex w-full flex-col overflow-hidden rounded-lg text-sm ring ring-border bg-card"><div class="flex items-center gap-2 px-3 py-2 text-[0.8125rem] font-medium leading-5 text-muted-foreground bg-[var(--nb-surface-sunken)]" role="tablist" aria-label="Package manager"><button role="tab" type="button" aria-selected="true" aria-controls="pm-panel-pm-720e07dd-552d-4284-9db6-58974202fffc-npm" id="pm-tab-pm-720e07dd-552d-4284-9db6-58974202fffc-npm" data-nb-pm-tab class="text-muted-foreground hover:bg-accent hover:text-foreground aria-selected:bg-selected aria-selected:text-foreground focus-visible:outline-ring m-0 cursor-pointer rounded-md border-0 bg-transparent px-2 py-0.5 text-xs leading-5 font-medium transition-colors focus-visible:outline-2 focus-visible:outline-offset-2">npm</button><button role="tab" type="button" aria-selected="false" aria-controls="pm-panel-pm-720e07dd-552d-4284-9db6-58974202fffc-yarn" id="pm-tab-pm-720e07dd-552d-4284-9db6-58974202fffc-yarn" data-nb-pm-tab class="text-muted-foreground hover:bg-accent hover:text-foreground aria-selected:bg-selected aria-selected:text-foreground focus-visible:outline-ring m-0 cursor-pointer rounded-md border-0 bg-transparent px-2 py-0.5 text-xs leading-5 font-medium transition-colors focus-visible:outline-2 focus-visible:outline-offset-2">yarn</button><button role="tab" type="button" aria-selected="false" aria-controls="pm-panel-pm-720e07dd-552d-4284-9db6-58974202fffc-pnpm" id="pm-tab-pm-720e07dd-552d-4284-9db6-58974202fffc-pnpm" data-nb-pm-tab class="text-muted-foreground hover:bg-accent hover:text-foreground aria-selected:bg-selected aria-selected:text-foreground focus-visible:outline-ring m-0 cursor-pointer rounded-md border-0 bg-transparent px-2 py-0.5 text-xs leading-5 font-medium transition-colors focus-visible:outline-2 focus-visible:outline-offset-2">pnpm</button><button role="tab" type="button" aria-selected="false" aria-controls="pm-panel-pm-720e07dd-552d-4284-9db6-58974202fffc-bun" id="pm-tab-pm-720e07dd-552d-4284-9db6-58974202fffc-bun" data-nb-pm-tab class="text-muted-foreground hover:bg-accent hover:text-foreground aria-selected:bg-selected aria-selected:text-foreground focus-visible:outline-ring m-0 cursor-pointer rounded-md border-0 bg-transparent px-2 py-0.5 text-xs leading-5 font-medium transition-colors focus-visible:outline-2 focus-visible:outline-offset-2">bun</button></div><div role="tabpanel" id="pm-panel-pm-720e07dd-552d-4284-9db6-58974202fffc-npm" aria-labelledby="pm-tab-pm-720e07dd-552d-4284-9db6-58974202fffc-npm" data-nb-pm-panel class="bg-card ring-border relative overflow-hidden rounded-lg text-inherit ring"><div class="flex items-stretch"><pre class="text-foreground my-0 min-w-0 grow overflow-x-auto border-0 bg-transparent px-4 py-3 font-mono text-sm leading-relaxed whitespace-pre"><code data-nb-pm-code>npm i agents@latest</code></pre><button type="button" data-nb-pm-copy data-nb-command="npm i agents@latest" aria-label="Copy to clipboard" class="border-border text-muted-foreground hover:text-foreground focus-visible:outline-ring m-0 flex shrink-0 cursor-pointer items-center justify-center border-0 border-l border-solid bg-transparent px-3 transition-colors focus-visible:outline-2 focus-visible:-outline-offset-2"><svg width="1em" height="1em" viewBox="0 0 256 256" class="h-[18px] w-[18px]" data-icon="ph:copy"><path fill="currentColor" d="M216 32H88a8 8 0 0 0-8 8v40H40a8 8 0 0 0-8 8v128a8 8 0 0 0 8 8h128a8 8 0 0 0 8-8v-40h40a8 8 0 0 0 8-8V40a8 8 0 0 0-8-8m-56 176H48V96h112Zm48-48h-32V88a8 8 0 0 0-8-8H96V48h112Z"/></svg><svg width="1em" height="1em" viewBox="0 0 256 256" class="hidden h-[18px] w-[18px]" data-icon="ph:check"><path fill="currentColor" d="m229.66 77.66l-128 128a8 8 0 0 1-11.32 0l-56-56a8 8 0 0 1 11.32-11.32L96 188.69L218.34 66.34a8 8 0 0 1 11.32 11.32"/></svg></button></div></div><div role="tabpanel" id="pm-panel-pm-720e07dd-552d-4284-9db6-58974202fffc-yarn" aria-labelledby="pm-tab-pm-720e07dd-552d-4284-9db6-58974202fffc-yarn" hidden data-nb-pm-panel class="bg-card ring-border relative overflow-hidden rounded-lg text-inherit ring"><div class="flex items-stretch"><pre class="text-foreground my-0 min-w-0 grow overflow-x-auto border-0 bg-transparent px-4 py-3 font-mono text-sm leading-relaxed whitespace-pre"><code data-nb-pm-code>yarn add agents@latest</code></pre><button type="button" data-nb-pm-copy data-nb-command="yarn add agents@latest" aria-label="Copy to clipboard" class="border-border text-muted-foreground hover:text-foreground focus-visible:outline-ring m-0 flex shrink-0 cursor-pointer items-center justify-center border-0 border-l border-solid bg-transparent px-3 transition-colors focus-visible:outline-2 focus-visible:-outline-offset-2"><svg width="1em" height="1em" viewBox="0 0 256 256" class="h-[18px] w-[18px]" data-icon="ph:copy"><path fill="currentColor" d="M216 32H88a8 8 0 0 0-8 8v40H40a8 8 0 0 0-8 8v128a8 8 0 0 0 8 8h128a8 8 0 0 0 8-8v-40h40a8 8 0 0 0 8-8V40a8 8 0 0 0-8-8m-56 176H48V96h112Zm48-48h-32V88a8 8 0 0 0-8-8H96V48h112Z"/></svg><svg width="1em" height="1em" viewBox="0 0 256 256" class="hidden h-[18px] w-[18px]" data-icon="ph:check"><path fill="currentColor" d="m229.66 77.66l-128 128a8 8 0 0 1-11.32 0l-56-56a8 8 0 0 1 11.32-11.32L96 188.69L218.34 66.34a8 8 0 0 1 11.32 11.32"/></svg></button></div></div><div role="tabpanel" id="pm-panel-pm-720e07dd-552d-4284-9db6-58974202fffc-pnpm" aria-labelledby="pm-tab-pm-720e07dd-552d-4284-9db6-58974202fffc-pnpm" hidden data-nb-pm-panel class="bg-card ring-border relative overflow-hidden rounded-lg text-inherit ring"><div class="flex items-stretch"><pre class="text-foreground my-0 min-w-0 grow overflow-x-auto border-0 bg-transparent px-4 py-3 font-mono text-sm leading-relaxed whitespace-pre"><code data-nb-pm-code>pnpm add agents@latest</code></pre><button type="button" data-nb-pm-copy data-nb-command="pnpm add agents@latest" aria-label="Copy to clipboard" class="border-border text-muted-foreground hover:text-foreground focus-visible:outline-ring m-0 flex shrink-0 cursor-pointer items-center justify-center border-0 border-l border-solid bg-transparent px-3 transition-colors focus-visible:outline-2 focus-visible:-outline-offset-2"><svg width="1em" height="1em" viewBox="0 0 256 256" class="h-[18px] w-[18px]" data-icon="ph:copy"><path fill="currentColor" d="M216 32H88a8 8 0 0 0-8 8v40H40a8 8 0 0 0-8 8v128a8 8 0 0 0 8 8h128a8 8 0 0 0 8-8v-40h40a8 8 0 0 0 8-8V40a8 8 0 0 0-8-8m-56 176H48V96h112Zm48-48h-32V88a8 8 0 0 0-8-8H96V48h112Z"/></svg><svg width="1em" height="1em" viewBox="0 0 256 256" class="hidden h-[18px] w-[18px]" data-icon="ph:check"><path fill="currentColor" d="m229.66 77.66l-128 128a8 8 0 0 1-11.32 0l-56-56a8 8 0 0 1 11.32-11.32L96 188.69L218.34 66.34a8 8 0 0 1 11.32 11.32"/></svg></button></div></div><div role="tabpanel" id="pm-panel-pm-720e07dd-552d-4284-9db6-58974202fffc-bun" aria-labelledby="pm-tab-pm-720e07dd-552d-4284-9db6-58974202fffc-bun" hidden data-nb-pm-panel class="bg-card ring-border relative overflow-hidden rounded-lg text-inherit ring"><div class="flex items-stretch"><pre class="text-foreground my-0 min-w-0 grow overflow-x-auto border-0 bg-transparent px-4 py-3 font-mono text-sm leading-relaxed whitespace-pre"><code data-nb-pm-code>bun add agents@latest</code></pre><button type="button" data-nb-pm-copy data-nb-command="bun add agents@latest" aria-label="Copy to clipboard" class="border-border text-muted-foreground hover:text-foreground focus-visible:outline-ring m-0 flex shrink-0 cursor-pointer items-center justify-center border-0 border-l border-solid bg-transparent px-3 transition-colors focus-visible:outline-2 focus-visible:-outline-offset-2"><svg width="1em" height="1em" viewBox="0 0 256 256" class="h-[18px] w-[18px]" data-icon="ph:copy"><path fill="currentColor" d="M216 32H88a8 8 0 0 0-8 8v40H40a8 8 0 0 0-8 8v128a8 8 0 0 0 8 8h128a8 8 0 0 0 8-8v-40h40a8 8 0 0 0 8-8V40a8 8 0 0 0-8-8m-56 176H48V96h112Zm48-48h-32V88a8 8 0 0 0-8-8H96V48h112Z"/></svg><svg width="1em" height="1em" viewBox="0 0 256 256" class="hidden h-[18px] w-[18px]" data-icon="ph:check"><path fill="currentColor" d="m229.66 77.66l-128 128a8 8 0 0 1-11.32 0l-56-56a8 8 0 0 1 11.32-11.32L96 188.69L218.34 66.34a8 8 0 0 1 11.32 11.32"/></svg></button></div></div><nb-pm-restore style="display:contents"></nb-pm-restore></div></div><script type="module" src="https://developers.cloudflare.com/home/runner/work/cloudflare-docs/cloudflare-docs/src/components/ui/package-managers/PackageManagerTabs.astro?astro&type=script&index=0&lang.ts"></script>

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