--- title: Agents SDK v0.7.0: Observability rewrite, keepAlive, and waitForMcpConnections description: Agents SDK v0.7.0 replaces the old console.log-based observability with diagnostics_channel events across 7 named channels, adds keepAlive() to prevent idle eviction during long-running work, and introduces waitForMcpConnections to guarantee MCP tools are ready before chat handlers run. image: https://developers.cloudflare.com/changelog-preview.png --- [Skip to content](#%5Ftop) # Changelog New updates and improvements at Cloudflare. [ Subscribe to RSS ](https://developers.cloudflare.com/changelog/rss/index.xml) [ View RSS feeds ](https://developers.cloudflare.com/fundamentals/new-features/available-rss-feeds/) ![hero image](https://developers.cloudflare.com/_astro/hero.CVYJHPAd_26AMqX.svg) [ ← Back to all posts ](https://developers.cloudflare.com/changelog/) ## Agents SDK v0.7.0: Observability rewrite, keepAlive, and waitForMcpConnections Mar 02, 2026 [ Agents ](https://developers.cloudflare.com/agents/)[ Workers ](https://developers.cloudflare.com/workers/) The latest release of the [Agents SDK ↗](https://github.com/cloudflare/agents) rewrites observability from scratch with `diagnostics_channel`, adds `keepAlive()` to prevent Durable Object eviction during long-running work, and introduces `waitForMcpConnections` so MCP tools are always available when `onChatMessage` runs. #### Observability rewrite The previous observability system used `console.log()` with a custom `Observability.emit()` interface. v0.7.0 replaces it with structured events published to [diagnostics channels](https://developers.cloudflare.com/workers/runtime-apis/nodejs/diagnostics-channel/) — silent by default, zero overhead when nobody is listening. Every event has a `type`, `payload`, and `timestamp`. Events are routed to seven named channels: | Channel | Event types | | ---------------- | ------------------------------------------------------------------------------------------------------------------------------------------------ | | agents:state | state:update | | agents:rpc | rpc, rpc:error | | agents:message | message:request, message:response, message:clear, message:cancel, message:error, tool:result, tool:approval | | agents:schedule | schedule:create, schedule:execute, schedule:cancel, schedule:retry, schedule:error, queue:retry, queue:error | | agents:lifecycle | connect, destroy | | agents:workflow | workflow:start, workflow:event, workflow:approved, workflow:rejected, workflow:terminated, workflow:paused, workflow:resumed, workflow:restarted | | agents:mcp | mcp:client:preconnect, mcp:client:connect, mcp:client:authorize, mcp:client:discover | Use the typed `subscribe()` helper from `agents/observability` for type-safe access: * [ JavaScript ](#tab-panel-1288) * [ TypeScript ](#tab-panel-1289) JavaScript ``` import { subscribe } from "agents/observability"; const unsub = subscribe("rpc", (event) => { if (event.type === "rpc") { console.log(`RPC call: ${event.payload.method}`); } if (event.type === "rpc:error") { console.error( `RPC failed: ${event.payload.method} — ${event.payload.error}`, ); } }); // Clean up when done unsub(); ``` Explain Code TypeScript ``` import { subscribe } from "agents/observability"; const unsub = subscribe("rpc", (event) => { if (event.type === "rpc") { console.log(`RPC call: ${event.payload.method}`); } if (event.type === "rpc:error") { console.error( `RPC failed: ${event.payload.method} — ${event.payload.error}`, ); } }); // Clean up when done unsub(); ``` Explain Code In production, all diagnostics channel messages are automatically forwarded to [Tail Workers](https://developers.cloudflare.com/workers/observability/logs/tail-workers/) — no subscription code needed in the agent itself: * [ JavaScript ](#tab-panel-1286) * [ TypeScript ](#tab-panel-1287) JavaScript ``` export default { async tail(events) { for (const event of events) { for (const msg of event.diagnosticsChannelEvents) { // msg.channel is "agents:rpc", "agents:workflow", etc. console.log(msg.timestamp, msg.channel, msg.message); } } }, }; ``` Explain Code TypeScript ``` export default { async tail(events) { for (const event of events) { for (const msg of event.diagnosticsChannelEvents) { // msg.channel is "agents:rpc", "agents:workflow", etc. console.log(msg.timestamp, msg.channel, msg.message); } } }, }; ``` Explain Code The custom `Observability` override interface is still supported for users who need to filter or forward events to external services. For the full event reference, refer to the [Observability documentation](https://developers.cloudflare.com/agents/api-reference/observability/). #### `keepAlive()` and `keepAliveWhile()` Durable Objects are evicted after a period of inactivity (typically 70-140 seconds with no incoming requests, WebSocket messages, or alarms). During long-running operations — streaming LLM responses, waiting on external APIs, running multi-step computations — the agent can be evicted mid-flight. `keepAlive()` prevents this by creating a 30-second heartbeat schedule. The alarm firing resets the inactivity timer. Returns a disposer function that cancels the heartbeat when called. * [ JavaScript ](#tab-panel-1284) * [ TypeScript ](#tab-panel-1285) JavaScript ``` const dispose = await this.keepAlive(); try { const result = await longRunningComputation(); await sendResults(result); } finally { dispose(); } ``` TypeScript ``` const dispose = await this.keepAlive(); try { const result = await longRunningComputation(); await sendResults(result); } finally { dispose(); } ``` `keepAliveWhile()` wraps an async function with automatic cleanup — the heartbeat starts before the function runs and stops when it completes: * [ JavaScript ](#tab-panel-1282) * [ TypeScript ](#tab-panel-1283) JavaScript ``` const result = await this.keepAliveWhile(async () => { const data = await longRunningComputation(); return data; }); ``` TypeScript ``` const result = await this.keepAliveWhile(async () => { const data = await longRunningComputation(); return data; }); ``` Key details: * **Multiple concurrent callers** — Each `keepAlive()` call returns an independent disposer. Disposing one does not affect others. * **AIChatAgent built-in** — `AIChatAgent` automatically calls `keepAlive()` during streaming responses. You do not need to add it yourself. * **Uses the scheduling system** — The heartbeat does not conflict with your own schedules. It shows up in `getSchedules()` if you need to inspect it. Note `keepAlive()` is marked `@experimental` and may change between releases. For the full API reference and when-to-use guidance, refer to [Schedule tasks — Keeping the agent alive](https://developers.cloudflare.com/agents/api-reference/schedule-tasks/#keeping-the-agent-alive). #### `waitForMcpConnections` `AIChatAgent` now waits for MCP server connections to settle before calling `onChatMessage`. This ensures `this.mcp.getAITools()` returns the full set of tools, especially after Durable Object hibernation when connections are being restored in the background. * [ JavaScript ](#tab-panel-1290) * [ TypeScript ](#tab-panel-1291) JavaScript ``` export class ChatAgent extends AIChatAgent { // Default — waits up to 10 seconds // waitForMcpConnections = { timeout: 10_000 }; // Wait forever waitForMcpConnections = true; // Disable waiting waitForMcpConnections = false; } ``` Explain Code TypeScript ``` export class ChatAgent extends AIChatAgent { // Default — waits up to 10 seconds // waitForMcpConnections = { timeout: 10_000 }; // Wait forever waitForMcpConnections = true; // Disable waiting waitForMcpConnections = false; } ``` Explain Code | Value | Behavior | | -------------------- | --------------------------------------------- | | { timeout: 10\_000 } | Wait up to 10 seconds (default) | | { timeout: N } | Wait up to N milliseconds | | true | Wait indefinitely until all connections ready | | false | Do not wait (old behavior before 0.2.0) | For lower-level control, call `this.mcp.waitForConnections()` directly inside `onChatMessage` instead. #### Other improvements * **MCP deduplication by name and URL** — `addMcpServer` with HTTP transport now deduplicates on both server name and URL. Calling it with the same name but a different URL creates a new connection. URLs are normalized before comparison (trailing slashes, default ports, hostname case). * **`callbackHost` optional for non-OAuth servers** — `addMcpServer` no longer requires `callbackHost` when connecting to MCP servers that do not use OAuth. * **MCP URL security** — Server URLs are validated before connection to prevent SSRF. Private IP ranges, loopback addresses, link-local addresses, and cloud metadata endpoints are blocked. * **Custom denial messages** — `addToolOutput` now supports `state: "output-error"` with `errorText` for custom denial messages in human-in-the-loop tool approval flows. * **`requestId` in chat options** — `onChatMessage` options now include a `requestId` for logging and correlating events. #### Upgrade To update to the latest version: Terminal window ``` npm i agents@latest @cloudflare/ai-chat@latest ```