Dev Tools & GitMCP RegistryremoteB · 62

ONCE — Exactly-Once Reliability for AI Agent Actions MCP server

Name: ONCE — Exactly-Once Reliability for AI Agent Actions
Author: GSterlingPress

io.github.GSterlingPress · Updated 1mo ago

Prevent duplicate AI-agent side effects with idempotency, verification, and durable receipts.

At a glance

ONCE — Exactly-Once Reliability for AI Agent Actions is an MCP server in the Dev Tools & Git category. It is hosted remotely and connects over HTTP, and declares no required credentials. It scores B (62/100) on the MCP Skills Hub health score as of Oct 28, 2026.

Source 0

One-click install

VS Code VS Code Insiders Cursor

Opens your editor and pre-fills the config. Your editor will ask before adding it.

How to install ONCE — Exactly-Once Reliability for AI Agent Actions in your AI client

Setup for Claude Code, Claude Desktop, Cursor, Codex, Windsurf, Cline and VS Code — copy-paste ready.

How to install ONCE — Exactly-Once Reliability for AI Agent Actions in Claude CodeAnthropic's agentic CLI

Add the server

bash

claude mcp add --transport http once https://optimistic-compassion-production.up.railway.app/mcp

2
Verify it's connected
bash
```
claude mcp list
```
Sharing it with your team?
Add `--scope project` to write it to .mcp.json in the repository root, which you can commit (with the secrets left as environment variables).
Use it in a session
Ask Claude to use the tools this server exposes. It discovers them automatically.

How to install ONCE — Exactly-Once Reliability for AI Agent Actions in Claude DesktopDesktop app (MCP config)

Open your MCP config
macOS: ~/Library/Application Support/Claude/claude_desktop_config.json · Windows: %APPDATA%\Claude\claude_desktop_config.json

Add this server

json

{
  "mcpServers": {
    "once": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-remote",
        "https://optimistic-compassion-production.up.railway.app/mcp"
      ]
    }
  }
}

Why the wrapper?
This is a remote (HTTP) server and Claude Desktop only launches local processes, so mcp-remote proxies the connection. It will open a browser window if the server needs OAuth.
Restart Claude Desktop
The tools appear under the 🔌 menu once the app reloads.

How to install ONCE — Exactly-Once Reliability for AI Agent Actions in CursorAI-first code editor

Create / edit .cursor/mcp.json in your project

json

{
  "mcpServers": {
    "once": {
      "url": "https://optimistic-compassion-production.up.railway.app/mcp"
    }
  }
}

Enable it
Cursor Settings → MCP → toggle the server on. Tools become available to the Composer/Agent.

How to install ONCE — Exactly-Once Reliability for AI Agent Actions in Codex CLIOpenAI coding agent

Add to ~/.codex/config.toml

toml

[mcp_servers.once]
command = "npx"
args = ["-y", "mcp-remote", "https://optimistic-compassion-production.up.railway.app/mcp"]

Why the wrapper?
Codex runs MCP servers as local processes, so mcp-remote bridges this HTTP endpoint to stdio.
Run Codex
Codex loads MCP servers from config.toml on startup and exposes their tools to the agent.

How to install ONCE — Exactly-Once Reliability for AI Agent Actions in WindsurfCodeium's agentic IDE

Edit ~/.codeium/windsurf/mcp_config.json

json

{
  "mcpServers": {
    "once": {
      "serverUrl": "https://optimistic-compassion-production.up.railway.app/mcp"
    }
  }
}

Reload
Windsurf → Cascade → refresh MCP servers. Cascade can now call the tools.

How to install ONCE — Exactly-Once Reliability for AI Agent Actions in ClineVS Code autonomous agent

Open Cline → MCP Servers → Configure
Adds to cline_mcp_settings.json.

Add the server

json

{
  "mcpServers": {
    "once": {
      "type": "streamableHttp",
      "url": "https://optimistic-compassion-production.up.railway.app/mcp"
    }
  }
}

How to install ONCE — Exactly-Once Reliability for AI Agent Actions in VS CodeCopilot / MCP support

Create .vscode/mcp.json

json

{
  "servers": {
    "once": {
      "type": "http",
      "url": "https://optimistic-compassion-production.up.railway.app/mcp"
    }
  }
}

Start it
VS Code shows a ▶ Start action above the server entry. Agent mode (Copilot Chat) can then use the tools.

What tools does ONCE — Exactly-Once Reliability for AI Agent Actions expose?

The server did not respond when we asked for its tool list. It may be offline, or it may not speak HTTP transport.

What the code can do

This is a remote server — nothing is installed or run on your machine, so there is no local code to analyze. What it can reach is described above: your requests go to the provider's host.

Before you install

Signals gathered from the source repo and package registry — not a safety verdict.

What it can reach

Third-party hosted service — Your requests and any data in them are sent to optimistic-compassion-production.up.railway.app.
No local execution — Nothing is installed or run on your machine.

Last commit 1 month ago — Actively maintained.
Repository created 2 months ago — Very new project with little track record yet.
0 GitHub stars — Very little community usage so far.
No license declared — Without a license the code is not legally reusable in a commercial project.

Client compatibility

Claude Code: NativeClaude Desktop: Via mcp-remoteCursor: NativeCodex CLI: Via mcp-remoteWindsurf: NativeCline: NativeVS Code: Native

Health score

B · 62

Maintenance, adoption, transparency and packaging — not a safety audit. How this is calculated

Maintenance30%98%
Last commit 45 days ago.
Adoption20%0%
0 stars.
Transparency20%50%
2/4: ✓ public source repo, ✗ declared license, ✓ documentation, ✗ discoverable tool list.
Provenance15%75%
Links to its own repository; package linkage unverified.
Packaging15%75%
Remote endpoint; authentication requirements not declared.

Documentation

Full README

ONCE

Never let an AI agent accidentally do the same consequential action twice.

ONCE is a tiny reliability layer for AI agents and automation. Use it when a retry could create a duplicate refund, charge, email, booking, order, webhook, or database mutation.

Try it in 30 seconds — no signup

bash

curl -X POST https://optimistic-compassion-production.up.railway.app/v1/demo \
  -H 'content-type: application/json' \
  -d '{"id":"hello-once"}'

Run it twice. The second receipt returns "duplicateSuppressed":true.

Get a free trial API key — no account

bash

curl -X POST https://optimistic-compassion-production.up.railway.app/v1/trial \
  -H 'content-type: application/json' \
  -d '{"name":"my-agent"}'

The experimental trial key includes 100 calls/month. Save it when issued: ONCE stores only its hash and cannot reveal it again. Trial issuance is rate-limited.

Live service

Base URL: https://optimistic-compassion-production.up.railway.app

GET /health — liveness
GET /ready — storage readiness
GET /version — deployed version
GET /v1/stats — privacy-safe aggregate adoption counters
GET /v1/activity — privacy-safe external activity summary
POST /v1/demo — safe public duplicate-suppression demo
POST /v1/trial — self-serve experimental API key
POST /v1/once — authenticated execution + verification
POST /mcp — MCP Streamable HTTP endpoint

Why ONCE

Agents see timeouts and ambiguous responses. A naive retry can repeat a side effect. ONCE uses an idempotency key, executes the action, checks authoritative post-state, and stores a durable receipt. A later retry with the same key returns the verified receipt instead of executing the action again.

Alternatives to ONCE — Exactly-Once Reliability for AI Agent Actions

Maintain ONCE — Exactly-Once Reliability for AI Agent Actions? Add a badge to your README

Shows its health grade, and links readers to install steps for every client.

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