Key Features

RPC Transport for MCP Connections

Agents can now connect to MCP servers in the same Worker using Durable Object bindings instead of HTTP URLs. This eliminates network round-trips and serialization overhead while keeping connections entirely within the Cloudflare runtime.

The implementation includes:

• Hibernation support — RPC connections automatically survive Durable Object hibernation; binding names and context properties persist to storage and restore on wake-up
• Connection deduplication — Repeated calls to addMcpServer with the same server name return the existing connection instead of creating duplicates
• Simplified transport — The RPC transport was rewritten and reduced from 609 to 245 lines, now using JSONRPCMessageSchema from the MCP SDK for validation

// Connect via Durable Object binding with optional per-user context
await this.addMcpServer("counter", env.MY_MCP, {
  props: { userId: "user-123", role: "admin" }
});

Optional OAuth for MCP

OAuth authentication is now opt-in rather than mandatory. Servers that don't require authentication can be connected with a single line of code. If a server responds with 401, the SDK throws a clear error message directing developers to enable the OAuth flow when needed.

Improved Schema Conversion

The JSON Schema to TypeScript converter now handles production edge cases:

• Circular reference and depth guards prevent stack overflows
• Support for $ref resolution with internal JSON Pointers
• Tuple support for prefixItems (JSON Schema 2020-12) and draft-07 arrays
• OpenAPI 3.0 nullable: true compatibility
• Per-tool error isolation ensures one malformed schema won't crash the full pipeline
• Missing inputSchema gracefully falls back to { type: "object" }

Reliability Improvements

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

• Tool denial flows — Denied approvals now correctly transition to output-denied status, improving Anthropic provider compatibility
• Streaming abort/cancel support — Properly cancels reader loops when abort signals fire
• Message deduplication — persistMessages() reconciles assistant messages by content and order
• Error handling — requestId now available in OnChatMessageOptions for pre-stream error responses
• Anthropic compatibility — redacted_thinking blocks are preserved during message sanitization
• Endpoint reliability — /get-messages handler moved to constructor wrapper, ensuring it works even when users override onRequest
• Tool API restoration — Client tool APIs (createToolsFromClientSchemas, clientTools, AITool) are undeprecated for runtime-defined tools
• Schema initialization — Fixed errors when calling getAITools() in onChatMessage

Getting Started

Update to the latest version with:

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

The type-safe API ensures HTTP and RPC paths cannot be mixed, catching configuration errors at compile time.