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CursorAnnouncement
Custom stores, custom tools, and auto-review for the Cursor SDK
Summary
The Cursor SDK’s TypeScript and Python releases add custom tools, auto-review, and nested subagents. Custom tools let developers pass function definitions through local.customTools, exposed via a built-in MCP server, making them available to all subagents. Auto-review routes local agent tool calls through a classifier; instructions in permissions.json control which calls run automatically and which are held for review. The SDK now supports a JSONL store for agent metadata as an alternative to SQLite, and developers can implement the LocalAgentStore interface for custom backends. Subagents can spawn their own subagents without additional configuration, and the release includes reliability and platform fixes.
Context
The Cursor SDK is a framework for building AI agents. This release adds several new capabilities to both the TypeScript and Python SDKs.
Approach / What changed
Developers can use custom tools by passing function definitions to local.customTools on Agent.create() or per send(). Auto-review is enabled by setting local.autoReview and configuring permissions.json with allow_instructions and block_instructions. Custom stores are selected by using SqliteLocalAgentStore, JsonlLocalAgentStore, or implementing the LocalAgentStore interface. Nested subagents work automatically.
Takeaways
Custom tools can be defined as function definitions and passed through local.customTools, exposed via a built-in MCP server, and are visible to all subagents.
Auto-review uses a classifier steered by natural-language instructions in permissions.json to decide which tool calls to allow automatically and which to hold for review.
The SDK now supports a JSONL store for agent metadata as an alternative to SQLite, and developers can implement the LocalAgentStore interface for custom persistence backends.
FAQ
How do I add custom tools to a Cursor SDK agent?
Pass function definitions through local.customTools on Agent.create() or per send(). The SDK exposes them via a built-in MCP server called custom-user-tools, making them available to all subagents.
How does auto-review work in the Cursor SDK?
Set local.autoReview to route tool calls through a classifier. Use permissions.json with autoRun.allow_instructions and autoRun.block_instructions to steer which calls run automatically and which are held for review.
Can I use a different storage backend for agent metadata?
Yes. You can use the built-in JSONL store (JsonlLocalAgentStore) instead of SQLite, or implement the LocalAgentStore interface to use an in-memory store, Postgres, or any other backend.
Source and freshness
- Source
- cursor.com
- Published
- Added to Yomu
Summaries are generated from the original by a language model. Check the original before relying on it.
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