agentmailbox-cursor

AgentMailbox — Context Sync for Cursor

Your context follows you. Not the tool.

AgentMailbox gives Cursor persistent memory across Composer sessions, tools, and restarts. When a session starts, check your mailbox and pick up exactly where the last session left off — including context from Claude Desktop, Antigravity, Continue, or any other MCP-aware tool.

Setup in Cursor

1. Add MCP Server

Go to Cursor Settings → MCP and add:

{
  "mcpServers": {
    "agentsmcp": {
      "command": "npx",
      "args": ["-y", "agentsmcp-adapter"],
      "env": {
        "AGENTSMCP_AGENT_ID": "cursor@local",
        "AGENTSMCP_SERVER": "http://localhost:3000"
      }
    }
  }
}

For the public demo server (no self-hosting required):

{
  "env": {
    "AGENTSMCP_SERVER": "https://hdnxa5c8yr.us-east-1.awsapprunner.com"
  }
}

2. Install Rules (Optional)

Copy the rules file to your project for always-on context sync:

mkdir -p .cursor/rules
cp skills/cursor/rules/agentmailbox.mdc .cursor/rules/

3. Start the Server (Self-Hosted)

npx agentsmcp-server

Workflows for Cursor

Session Start — Restore Context

When opening a project or starting a new Composer session:

Tool: agentsmcp_receive

This returns the full context frame:

• snapshot — Last sender's state
• threadSummaryStructured — Decisions, open questions, artifacts from the thread
• recentMessages — Last 10 messages verbatim

Summarize for the user: "You were working on [X]. Open questions: [Y]."

Composer Multi-File Edits

Before starting a multi-file edit in Composer, sync the relevant thread:

Tool: agentsmcp_sync
Arguments: { "threadId": "<thread-id>" }

After completing the edit, record what changed:

Tool: agentsmcp_send
Arguments:
  to: "cursor@local"
  body: {
    "composerEdit": "Refactored auth module",
    "filesChanged": ["src/auth.ts", "src/middleware.ts", "tests/auth.test.ts"],
    "decisions": ["Using JWT with 24h expiry", "Middleware validates on every route"],
    "status": "complete"
  }