ST-2026-042 · Runtimes & developer platforms
Cloudflare Agents SDK 0.20 deprecates McpAgent and MCP SDK v1 call surfaces
Agents SDK v0.20.0 deprecated and feature-froze McpAgent, deprecated older callTool overloads and scheduled a v1-server handler overload for removal in the next major version.
Previous state
Agent applications could use McpAgent, v1 createMcpHandler signatures and legacy callTool overloads.
Current state
Cloudflare directs applications toward MCP SDK v2 factories and handlers, with a temporary legacy bridge for sessionful features.
Affected users
Who needs to care
Developers maintaining Cloudflare Agents and Model Context Protocol servers.
Required response
What to do
Adopt MCP SDK v2 patterns, isolate legacy bridge use and test sessionful and stateless behaviour before the next major release.
Evidence boundary
What the source does not prove
No removal version is stated for McpAgent or all legacy callTool overloads, and the next major release has no published date.
Lifecycle history
Dated event sequence
- Change documented
Agents SDK v0.20.0 deprecated and feature-froze McpAgent, deprecated older callTool overloads and scheduled a v1-server handler overload for removal in the next major version.
Evidence ledger
First-party sources
- 01Cloudflare Developers — Agents SDK v0.20.0 and MCP SDK v2
Official product documentation or changelog · 2026-07-27
Open official source ↗ - 02Cloudflare Developers — Migrate to MCP SDK v2
Official migration guide · 2026-07-27
Open official source ↗