Magic MCP vs SendLetter
A side-by-side look at the Magic MCP and SendLetter MCP servers: transport, auth, tools, quality signals, and the config to install either one in Claude, Cursor, Windsurf or VS Code.
Verdict: choose Magic MCP for architecture & design work as a local process; choose SendLetter for delivery. You can also run both side by side in one mcpServers block.
Which MCP server should you choose?
Choose Magic MCP when
- You need dedicated capabilities in the Architecture & Design domain.
- You prefer a local stdio subprocess transport.
- Its auth model fits you: API key required.
- You have the keys it needs:
TWENTY_FIRST_API_KEY, API_KEY_21ST.
Choose SendLetter when
- You need dedicated capabilities in the Delivery domain.
- You have the keys it needs:
SENDLETTER_API_KEY, SENDLETTER_WEBHOOK_SECRET.
Feature & specification comparison
Rows where the two servers differ are marked.
| Spec | ||
|---|---|---|
| Category | Architecture & Design | Delivery |
| Quality signal | 53/100 · Good | 31/100 · Emerging |
| Install command | Confirmed | Not confirmed yet |
| Transport | Local subprocess (stdio) | — |
| Auth | API key required | Not declared |
| Pricing | Paid service | Not declared |
| Required env vars | TWENTY_FIRST_API_KEYAPI_KEY_21ST | SENDLETTER_API_KEYSENDLETTER_WEBHOOK_SECRET |
| Verified owner | Community listing | Community listing |
| GitHub stars | 6,138 | 0 |
| Directory activity | 16 views 1 installs 0 upvotes | 1 views 0 installs 0 upvotes |
| Tools | Not listed | Not listed |
| Full listing | View Magic MCP | View SendLetter |
Tools & capabilities
Magic MCP tools
No tool names declared yet. Check the project README from the listing page.
SendLetter tools
No tool names declared yet. Check the project README from the listing page.
Ready-to-paste client configs
Paste either block (or both) into your client config, e.g. claude_desktop_config.json or ~/.cursor/mcp.json. We only show a config when the install command is confirmed.
Magic MCP
{
"mcpServers": {
"21st-dev-magic-mcp": {
"command": "npx",
"args": [
"-y",
"@21st-dev/cli@latest"
],
"env": {
"TWENTY_FIRST_API_KEY": "YOUR_TWENTY_FIRST_API_KEY_HERE",
"API_KEY_21ST": "YOUR_API_KEY_21ST_HERE"
}
}
}
}
SendLetter
No confirmed install command for SendLetter yet — follow the setup steps linked from its listing page rather than a guessed package name.