Tag: typescript

Protocol revision 2026-07-28 deleted Mcp-Session-Id, the initialize handshake, resources/subscribe, ping, logging/setLevel and SSE resumability. An automated survey of 1000 open source MCP servers found 90% reference the session ID nowhere. Here is what the other 10% has to rewrite, with verified code on @modelcontextprotocol/server 2.0.0.

A write tool that asks before it writes needs three things the MCP SDK does not give you: an approval bound to the exact diff, a precondition on the file it previewed, and an integrity-protected requestState. Verified end to end on @modelcontextprotocol/server 2.0.0 against protocol revision 2026-07-28, including the argument-swap that gets past a naive confirm.

Mapping 200 internal REST endpoints to 200 MCP tools puts 200 KB of JSON schema in front of every request. The 2026-07-28 spec also made the usual escape hatch illegal: tools/list MUST NOT vary per-connection, so per-session dynamic registration is gone. Here are the three levers that still work, with measured wire sizes and verified code on @modelcontextprotocol/server 2.0.0.

A step-by-step checklist for retiring a hand-rolled while-loop agent and running the same job on @cursor/sdk 1.0.26. The tool bodies survive, the loop does not, and three things you probably rely on have no equivalent: a system prompt string, a tool allowlist, and per-turn control.

The legacy HTTP+SSE transport used two endpoints and a sticky connection. Streamable HTTP uses one. Here is the step-by-step migration for the TypeScript and Python SDKs, the client configs you have to repoint, and the proxy buffering gotcha that makes the new endpoint look broken.

A step-by-step checklist for lifting a hand-rolled Anthropic tool-calling loop onto a standalone MCP server. The tool bodies move almost verbatim; what changes is where the schema comes from, how results are wrapped, and how errors cross the process boundary.

Define named subagents on agents in the Cursor SDK, let a code-reviewer delegate to a test-writer through the built-in Agent tool, and understand the real nesting depth cap: a subagent spawned by another subagent cannot spawn further ones, despite the changelog's 'and so on'.

By default a local Cursor SDK agent runs every tool call without asking. Set local.autoReview to route Shell, MCP, and Fetch calls through the classifier, then steer it with the autoRun block in permissions.json. With code, the three-step evaluation order, and why none of it is a security boundary.

The Cursor SDK already persists agent state to disk so Agent.resume() can pick a conversation back up after a crash. This walks the SqliteLocalAgentStore default, the JsonlLocalAgentStore you can commit to git, and how to implement the LocalAgentStore interface for Postgres, Redis, or an in-memory CI store.

Pass local.customTools to a Cursor SDK agent and the model calls your in-process functions through the built-in custom-user-tools MCP server. No stdio handshake, no separate process, no transport bugs. Local agents only: cloud agents throw ConfigurationError.