← Back
Cloudflare
Cloudflare Agents SDK v0.6.0 adds RPC transport for MCP, simplifies OAuth setup
Cloudflare Workers · releasefeaturesdkapi · developers.cloudflare.com ↗

RPC Transport for MCP Connections

Agents can now connect to MCP servers using Durable Object bindings instead of HTTP URLs, eliminating network round-trips and serialization overhead. Connections stay entirely within the Cloudflare runtime, improving performance and reducing latency for agent-to-server communication.

Key features include:

  • Hibernation support — RPC connections automatically survive Durable Object hibernation, with binding names and props persisted and restored
  • Deduplication — Multiple calls to addMcpServer() with the same server name return the existing connection instead of creating duplicates
  • Smaller footprint — Transport internals reduced from 609 to 245 lines, now using JSONRPCMessageSchema from the MCP SDK for validation

Simplified OAuth Configuration

OAuth is now optional for MCP connections. Servers that don't require authentication can be configured with a single line of code. If a server requires authentication, the SDK returns a clear error message guiding developers to enable the OAuth flow via the callbackHost option.

Enhanced Schema Conversion and Reliability

The JSON Schema to TypeScript converter now handles edge cases that previously caused crashes:

  • Circular reference and depth guards to prevent stack overflows
  • Internal JSON Pointer resolution (#/definitions/, #/$defs/, #)
  • Tuple support for both JSON Schema 2020-12 (prefixItems) and draft-07
  • OpenAPI 3.0 nullable: true support
  • Per-tool error isolation so one malformed schema doesn't crash the entire pipeline

AI Chat Improvements

The @cloudflare/ai-chat library receives multiple reliability fixes:

  • Tool denial flow — Properly handles denied tool approvals with Anthropic provider compatibility
  • Streaming improvements — Abort signal support and proper reader cleanup
  • Message persistence — Deduplication of assistant messages prevents duplicate rows when clients resend history
  • Anthropic compatibility — redacted_thinking blocks are now preserved during sanitization
  • Error handling — Added requestId support in OnChatMessageOptions for pre-stream failures
  • Restored client tool APIs — Previously deprecated methods are back for runtime-defined tools

Getting Started

Update to the latest version with:

npm i agents@latest @cloudflare/ai-chat@latest