# MCP in Cursor

Cursor is an AI-powered IDE based on VS Code. With Synapse MCP, Cursor gains
persistent memory across sessions — it remembers your project decisions,
codebase patterns, and past debugging sessions.

## Prerequisites

- Cursor IDE installed (<https://cursor.com>)
- Node.js 18+
- Your Synapse Mind Key

## Setup

### Step 1: Open Cursor Settings

In Cursor:

1. Open Settings (Cmd+, on macOS, Ctrl+, on Windows/Linux)
2. Search for "MCP" or navigate to `Cursor Settings → MCP Servers`

### Step 2: Add Synapse MCP Server

Click "Add MCP Server" and configure:

| Field | Value |
|-------|-------|
| Name | `synapse` |
| Type | `stdio` |
| Command | `npx -y synapse-mcp-api@latest` |
| Env | `SYNAPSE_MIND_KEY=mk_YOUR_KEY, SYNAPSE_URL=https://synapse.schaefer.zone` |

### Step 3: Edit config.json directly (alternative)

Cursor stores MCP config in `~/.cursor/config.json`:

```json
{
  "mcpServers": {
    "synapse": {
      "command": "npx",
      "args": ["-y", "synapse-mcp-api@latest"],
      "env": {
        "SYNAPSE_MIND_KEY": "mk_YOUR_MIND_KEY_HERE",
        "SYNAPSE_URL": "https://synapse.schaefer.zone"
      }
    }
  }
}
```

### Step 4: Restart Cursor

Fully restart Cursor (Cmd+Q and reopen on macOS).

## Verify It Works

In Cursor's chat panel (Cmd+L):

```
recall all my memories
```

Cursor should call `memory_recall` and respond with your stored memories.

## Common Patterns

### Project onboarding

When opening a new project:

```
recalling project context — what do I know about this codebase?
```

Cursor calls `memory_recall` and continues work where you left off.

### Architecture decisions

```
store this decision: "Using Fastify instead of Express for this project
because of schema validation. Date: 2026-06-27."
```

Cursor stores it as a `project` memory with `high` priority.

### Debugging history

```
what bugs have I hit in this codebase?
```

Cursor searches for `mistake` memories and reminds you of past fixes.

### Cross-session code patterns

```
search memories: "authentication pattern"
```

Cursor finds memories about auth implementations you've done before.

## Troubleshooting

### MCP server not connecting

1. Verify Node.js: `node --version` (≥ 18)
2. Test MCP server: `npx -y synapse-mcp-api@latest` (should start without errors)
3. Check Cursor's MCP logs (View → Output → MCP)
4. Restart Cursor fully

### Tools not appearing

- Check `~/.cursor/config.json` is valid JSON
- Verify `SYNAPSE_MIND_KEY` env var is set
- Check Cursor version supports MCP (≥ 0.42)

### Mind Key invalid

```bash
# Test your Mind Key directly
curl -H "Authorization: Bearer mk_YOUR_KEY" \
     https://synapse.schaefer.zone/memory/recall
```

## Next Steps

- [Claude Desktop Setup](/docs/mcp/claude-desktop)
- [Continue.dev Setup](/docs/mcp/continue)
- [Persistent LLM Agent Guide](/docs/guides/persistent-llm-agent)