Once
Rank #2,979io.github.stringsofthemind-oss/once
Execution-safety MCP for AI coding agents protecting consequential writes from unsafe retries.
Once is a Model Context Protocol (MCP) server published by stringsofthemind-oss. It ranks #2,979 of 137,492 servers tracked on MCP Toplist. Once is listed on Official MCP, with 5 tracked versions. It was first listed on Sep 20, 2026 and most recently updated on Sep 27, 2026.
Ranks ahead of 134,513 of 137,492 servers on MCP Toplist.
Use Once
No credentials or required configuration declared — add it to your MCP client and go.
claude mcp add once -e "ONCE_API_KEY=<your ONCE_API_KEY>" -- npx -y @once-agent/mcpReplace each placeholder with your own value before saving.
[mcp_servers.once]
command = "npx"
args = ["-y", "@once-agent/mcp"]
[mcp_servers.once.env]
ONCE_API_KEY = "<your ONCE_API_KEY>"Add to ~/.codex/config.toml. Replace each placeholder with your own value before saving.
{
"mcpServers": {
"once": {
"command": "npx",
"args": [
"-y",
"@once-agent/mcp"
],
"env": {
"ONCE_API_KEY": "<your ONCE_API_KEY>"
}
}
}
}Add to claude_desktop_config.json (Settings → Developer → Edit Config). Replace each placeholder with your own value before saving.
{
"mcpServers": {
"once": {
"command": "npx",
"args": [
"-y",
"@once-agent/mcp"
],
"env": {
"ONCE_API_KEY": "<your ONCE_API_KEY>"
}
}
}
}Add to ~/.cursor/mcp.json (global) or .cursor/mcp.json (per project). Replace each placeholder with your own value before saving.
{
"servers": {
"once": {
"type": "stdio",
"command": "npx",
"args": [
"-y",
"@once-agent/mcp"
],
"env": {
"ONCE_API_KEY": "<your ONCE_API_KEY>"
}
}
}
}Save as .vscode/mcp.json in your workspace. Replace each placeholder with your own value before saving.
{
"mcpServers": {
"once": {
"command": "npx",
"args": [
"-y",
"@once-agent/mcp"
],
"env": {
"ONCE_API_KEY": "<your ONCE_API_KEY>"
}
}
}
}Add to ~/.codeium/windsurf/mcp_config.json. Replace each placeholder with your own value before saving.
{
"mcpServers": {
"once": {
"command": "npx",
"args": [
"-y",
"@once-agent/mcp"
],
"env": {
"ONCE_API_KEY": "<your ONCE_API_KEY>"
}
}
}
}Replace each placeholder with your own value before saving.
Show your rank
Maintain this server? Add the live rank badge to your README — it updates automatically as the leaderboard changes.
[](https://mcptoplist.com/server/io.github.stringsofthemind-oss%2Fonce)<a href="https://mcptoplist.com/server/io.github.stringsofthemind-oss%2Fonce"><img src="https://mcptoplist.com/badge/io.github.stringsofthemind-oss%2Fonce.svg" alt="MCP Toplist: Top 5% of 137,492" /></a>Variants: append ?metric=score or ?metric=stars to the image URL.
Listed on 1 registry
stringsofthemind-oss
Available versions (5)
| Version | Published |
|---|---|
| 0.1.5 | Sep 27, 2026 |
| 0.1.3 | Sep 22, 2026 |
| 0.1.2 | Sep 20, 2026 |
| 0.1.1 | Sep 20, 2026 |
| 0.1.0 | Sep 20, 2026 |
Frequently asked questions
- Who maintains Once?
- Once is maintained by stringsofthemind-oss, which publishes 1 MCP server (5 total versions) tracked on MCP Toplist.
- Is Once listed on the Official MCP Registry?
- Yes — Once is listed on the Official MCP Registry.
- How many versions does Once have?
- MCP Toplist tracks 5 versions of Once, most recently published on Sep 27, 2026.
- Where can I find the source code for Once?
- The source code for Once is hosted at github.com/stringsofthemind-oss/once.
Do you run this server?
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