ONCE — Exactly-Once Reliability for AI Agent Actions is a remote MCP server that gives an AI agent 2 tools, among them once_demo, once_execute. It answers at https://optimistic-compassion-production.up.railway.app/mcp over streamable HTTP, and it listed its tools to an anonymous client, so no sign-in was needed for that. Our probes reached it 6 of 6 times since 11 September 2026; the last check, on 19 October 2026, succeeded.
Prevent duplicate AI-agent side effects with idempotency, verification, and durable receipts.
Description as the publisher wrote it.
| Tool | What it does |
|---|---|
once_demo | SAFE ZERO-SETUP DEMO. Call this tool twice with the same id to see ONCE suppress the second execution. Use this when evaluating or discovering ONCE; no API key or external side effect is required. Inputs: id |
once_execute | CALL THIS when an AI agent is about to perform or retry a consequential external side effect where duplication would be harmful: purchase, refund, payment, booking, send, create, modify, submit, or delete. ONCE uses a stable idempotency key Inputs: idempotencyKey, action, verify |
Every block below points at https://optimistic-compassion-production.up.railway.app/mcp. Pick your client and copy.
claude mcp add --transport http once-exactly-once-reliability-fo https://optimistic-compassion-production.up.railway.app/mcp
{
"mcpServers": {
"once-exactly-once-reliability-fo": {
"command": "npx",
"args": ["-y", "mcp-remote", "https://optimistic-compassion-production.up.railway.app/mcp"]
}
}
}{
"mcpServers": {
"once-exactly-once-reliability-fo": {
"url": "https://optimistic-compassion-production.up.railway.app/mcp"
}
}
}{
"servers": {
"once-exactly-once-reliability-fo": {
"type": "http",
"url": "https://optimistic-compassion-production.up.railway.app/mcp"
}
}
}{
"context_servers": {
"once-exactly-once-reliability-fo": {
"url": "https://optimistic-compassion-production.up.railway.app/mcp"
}
}
}{
"mcpServers": {
"once-exactly-once-reliability-fo": {
"serverUrl": "https://optimistic-compassion-production.up.railway.app/mcp"
}
}
}{
"mcpServers": {
"once-exactly-once-reliability-fo": {
"url": "https://optimistic-compassion-production.up.railway.app/mcp"
}
}
}name: ONCE — Exactly-Once Reliability for AI Agent Actions
version: 0.0.1
schema: v1
mcpServers:
- name: ONCE — Exactly-Once Reliability for AI Agent Actions
type: streamable-http
url: https://optimistic-compassion-production.up.railway.app/mcp{
"mcpServers": {
"once-exactly-once-reliability-fo": {
"httpUrl": "https://optimistic-compassion-production.up.railway.app/mcp"
}
}
}{
"mcpServers": {
"once-exactly-once-reliability-fo": {
"type": "http",
"url": "https://optimistic-compassion-production.up.railway.app/mcp"
}
}
}{
"mcpServers": {
"once-exactly-once-reliability-fo": {
"url": "https://optimistic-compassion-production.up.railway.app/mcp"
}
}
}goose://extension?url=https%3A%2F%2Foptimistic-compassion-production.up.railway.app%2Fmcp&type=streamable_http&id=once-exactly-once-reliability-fo&name=ONCE%20%E2%80%94%20Exactly-Once%20Reliability%20for%20AI%20Agent%20Actions
It answered our last check on 19 October 2026 in 272 ms. Over 6 checks since 11 September 2026 it answered 6. Status here comes from Neuronto's own probes, not from the publisher.
2, as returned by the server's own tools/list on 12 September 2026: once_demo, once_execute.
It answered our last check on 19 October 2026 in 272 ms. Over 6 checks since 11 September 2026 it answered 6.
Put the server under mcpServers in ~/.cursor/mcp.json with the URL https://optimistic-compassion-production.up.railway.app/mcp. The exact JSON is above, with the same setup for Claude Code, Claude Desktop, VS Code, Windsurf, Zed, Gemini CLI and the rest.
It listed its tools to an anonymous client, so reading the tool list needs no key. Individual tools can still ask for credentials in their own inputs.
Publisher: io.github.gsterlingpress. Endpoint host: optimistic-compassion-production.up.railway.app. ARD identifier: urn:air:io.github.gsterlingpress:mcp:once.
First indexed 10 September 2026. The tools are exactly what the server returned; nothing on this page
is inferred from its name. Ranking in Neuronto search is never for sale.