ONCE — Exactly-Once Reliability for AI Agent Actions
REMOTE · OPTIMISTIC-COMPASSION-PRODUCTION.UP.RAILWAY.APP · SCANNED OCT 4
Prevent duplicate AI-agent side effects with idempotency, verification, and durable receipts.
Available components
How this component scores in each security and reliability category. Every signal is checked automatically against the live server, and we only credit what we can confirm. How we score → Why this is hard to score →
Endpoint Security57
- The endpoint's TLS certificate is valid, in date, and uses a strong key. View diagnostics → Pass
- Authorisation not fully verified: no authorisation is required to call this server, and 2 tool(s) never declared a destructiveHint. The MCP spec treats an absent hint as destructive by default, so we cannot call this surface safe. See how to fix → View diagnostics → Unverified
- HTTPS is enforced; there's no plaintext access path. View diagnostics → Pass
- HSTS check failed: the Strict-Transport-Security header is absent. See how to fix → View diagnostics → Fail
- DNSSEC check failed: this domain isn't protected by DNSSEC. See how to fix → View diagnostics → Fail
Transport & Reachability100
- Verified streamable-http transport via a live MCP handshake. View diagnostics → Pass
Schema Quality & AI Usability78
- AI-judged instruction clarity (excellent).Pass
- Tool/resource definitions use about 272 tokens (~136/item across 2 items; 2 tools + 0 resources), lean.Pass
- Usage-examples check failed: none of the tools include examples. See how to fix → Fail
Stability & Change Management100
- No destabilizing schema changes in the last 30 days.Pass
Tool Coverage83
- 100% of tools have a non-trivial description (not blank, and not just the tool's name).Pass
- 50% of tool parameters carry a description.Partial
Tool Safety75
- No prompt-injection markers were found in the server instructions, tool names or descriptions we captured.Pass
- 0 of 1 tool(s) whose name or description implies an irreversible operation declare an MCP destructiveHint annotation; "once_execute" implies "execute" and declares no destructiveHint at all, which the MCP spec reads as destructive by default. See how to fix → Fail
- An AI judge read all 3 captured unit(s) of tool text and found none that tries to manipulate the model reading it.Pass
Capabilities100
- Implements a supported MCP spec version (2025-11-25); the latest is 2026-07-28.Pass
How do I install the ONCE — Exactly-Once Reliability for AI Agent Actions MCP server?
ONCE — Exactly-Once Reliability for AI Agent Actions is a hosted endpoint at https://optimistic-compassion-production.up.railway.app/mcp, so there is nothing to install locally. Ready-made configuration for Claude, Cursor, VS Code, Codex and 5 more is on this page, copied from each client's own documentation.
remote · optimistic-compassion-production.up.railway.app
claude mcp add --transport http gsterlingpress-once 'https://optimistic-compassion-production.up.railway.app/mcp'
{
"mcpServers": {
"gsterlingpress-once": {
"url": "https://optimistic-compassion-production.up.railway.app/mcp"
}
}
} {
"servers": {
"gsterlingpress-once": {
"type": "http",
"url": "https://optimistic-compassion-production.up.railway.app/mcp"
}
}
} [mcp_servers.gsterlingpress-once] url = "https://optimistic-compassion-production.up.railway.app/mcp"
{
"$schema": "https://opencode.ai/config.json",
"mcp": {
"gsterlingpress-once": {
"type": "remote",
"url": "https://optimistic-compassion-production.up.railway.app/mcp",
"enabled": true
}
}
} openclaw mcp add gsterlingpress-once --url 'https://optimistic-compassion-production.up.railway.app/mcp' --transport streamable-http
mcp_servers:
gsterlingpress-once:
url: "https://optimistic-compassion-production.up.railway.app/mcp" {
"McpServers": {
"gsterlingpress-once": {
"Transport": "http",
"Url": "https://optimistic-compassion-production.up.railway.app/mcp"
}
}
} assistant mcp add gsterlingpress-once -t streamable-http -u 'https://optimistic-compassion-production.up.railway.app/mcp'
{
"mcpServers": {
"gsterlingpress-once": {
"type": "http",
"url": "https://optimistic-compassion-production.up.railway.app/mcp"
}
}
} The mcpServers block is a cross-client convention. Remote transports vary, so check your client's docs.
Every change we have recorded for this component, newest first. Security-relevant changes are always shown. ▲ marks a change for the better, ▼ a change for the worse; unmarked changes are neutral.
- 28 Sept 26 0
- We updated how we score, so this day's move reflects our rubric, not a change to the server See what changed → functional
- 25 Sept 26 0
- We updated how we score, so this day's move reflects our rubric, not a change to the server See what changed → functional
- 10 Sept 26 0
- Stability: 0.97 → pass security
- 9 Sept 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 93 to 97. That category is still filling its 30-day observation window: 28 days of observed history at the previous scan, 29 at this one. The score rises as the window fills, whether or not the server changes.
- 7 Sept 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 87 to 90. That category is still filling its 30-day observation window: 26 days of observed history at the previous scan, 27 at this one. The score rises as the window fills, whether or not the server changes.
- 26 Aug 26 0
- We updated how we score, so this day's move reflects our rubric, not a change to the server See what changed → functional
- 14 Aug 26 0
- Server version: 0.8.1 → 0.8.2 functional
- 12 Aug 26 0
- The server rewrote its instructions, which are the text every model session reads security
- Tool “once_demo” rewrote its description, which is the text the model reads security
- Tool “once_execute” rewrote its description, which is the text the model reads security
- Schema quality: 60 → 136 ▼ functional
- Tool coverage: 0% → 50% ▲ functional
- Stability: unverified → 0.03 ▲ functional
- Schema quality: good → excellent functional
- Server version: 0.8.0 → 0.8.1 functional
- “once_demo” reworded the description of “id” cosmetic
- “once_execute” reworded the description of “idempotencyKey” cosmetic
- Tool “once_demo” changed its title: ONCE Duplicate Suppression Demo → Try ONCE Duplicate Suppression cosmetic
- Tool “once_execute” changed its title: Execute Consequential Action Once → Prevent Duplicate Consequential Agent Actions cosmetic
Diagnostic detail from the automated scan of this channel: what the scanner observed at each step, so you can see exactly where a check passed or failed. It is informational only and never changes the trust score.
Captured 6 Oct 2026 · Probed https://optimistic-compassion-production.up.railway.app/mcp
TLS valid
Negotiated TLS 1.3 with TLS_AES_128_GCM_SHA256 .
| Subject | Issuer | Valid from | Valid until | Key | Signature | Serial |
|---|---|---|---|---|---|---|
| CN=*.up.railway.app | CN=YE2,O=Let's Encrypt,C=US | 27 Sept 2026 | 26 Dec 2026 | ECDSA 256 | ECDSA-SHA384 | 618edc56941aa1165ddb080bf9f799eb7c1 |
| SANs: *.up.railway.app, up.railway.app | ||||||
| CN=YE2,O=Let's Encrypt,C=US (CA) | CN=Root YE,O=ISRG,C=US | 3 Sept 2025 | 2 Sept 2028 | ECDSA 384 | ECDSA-SHA384 | 4df3b15dd6c0784c507cd37b58e6f115 |
| CN=Root YE,O=ISRG,C=US (CA) | CN=ISRG Root X2,O=Internet Security Research Group,C=US | 13 May 2026 | 2 Sept 2032 | ECDSA 384 | ECDSA-SHA384 | 872165fc34b6e5fba8add5b3705fb53a |
| CN=ISRG Root X2,O=Internet Security Research Group,C=US (CA) | CN=ISRG Root X1,O=Internet Security Research Group,C=US | 13 May 2026 | 2 Sept 2032 | ECDSA 384 | SHA256-RSA | 6c8f1dc727c7117f7baf853ac980f9cd |
Background: What to check on a remote MCP endpoint →
DNSSEC insecure
Validation of optimistic-compassion-production.up.railway.app. — Not signed
| Zone | DS | Keys | Algorithms | Outcome |
|---|---|---|---|---|
| . | trust_anchor | 20326, 38696 | 8, 8 | Verified |
| app. | present | 23684 | 8 | Verified |
| railway.app. | absent | Unsigned (proven) parent-signed NSEC/NSEC3 proves an unsigned delegation |
Authentication No authorisation required
The endpoint answered without asking for a token. Anyone who knows the URL can reach it.
| Result | No authorisation required |
|---|---|
| HTTP status | 200 |
| Header | Value |
|---|---|
| x-content-type-options | nosniff |
| x-frame-options | DENY |
| referrer-policy | no-referrer |
Background: How OAuth 2.1 works in the 2026 MCP spec →
Transports 2 probes
| Transport | URL | Outcome | Status | Location |
|---|---|---|---|---|
| streamable-http | https://optimistic-compassion-production.up.railway.app/mcp | Verified | 200 | |
| http (plaintext) | http://optimistic-compassion-production.up.railway.app/mcp | HTTPS enforced | 301 | https://optimistic-compassion-production.up.railway.app/mcp |
The tools this component advertises to a client, with an estimated token cost for each. Expand a tool to see its parameters and schema. The per-tool counts are indicative and are not scored directly; the schema's total context footprint is one signal in Schema Quality & AI Usability. A tool's description is untrusted text the model reads on every call, which is what makes this list a security surface and not just an inventory: how tool poisoning works →
once_demo Try ONCE Duplicate Suppression ~77
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.
| Name | Type | Req | Description |
|---|---|---|---|
| id | string | yes | Any stable demo id. Reuse the SAME id on the second call to prove duplicate suppression. |
No output schema declared.
No examples provided.
once_execute Prevent Duplicate Consequential Agent Actions ~114
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, executes the action, verifies authoritative post-state, and suppresses verified retries.
| Name | Type | Req | Description |
|---|---|---|---|
| action | object | yes | – |
| idempotencyKey | string | yes | Stable key representing this one intended real-world action. Reuse it for retries. |
| verify | object | yes | – |
No output schema declared.
No examples provided.
What is the ONCE — Exactly-Once Reliability for AI Agent Actions MCP server?
ONCE — Exactly-Once Reliability for AI Agent Actions is an MCP server listed in the public MCP registry as io.github.GSterlingPress/once. Prevent duplicate AI-agent side effects with idempotency, verification, and durable receipts. This page covers its hosted endpoint (https://optimistic-compassion-production.up.railway.app/mcp).
Is the ONCE — Exactly-Once Reliability for AI Agent Actions MCP server safe to use?
ONCE — Exactly-Once Reliability for AI Agent Actions scores 76 out of 100 on VerifyMCP. That is a record of what we were able to check automatically, not an endorsement. The category breakdown on this page shows every signal behind the number, including the ones we could not confirm.
What tools does the ONCE — Exactly-Once Reliability for AI Agent Actions MCP server expose?
ONCE — Exactly-Once Reliability for AI Agent Actions exposes 2 tools: once_demo, once_execute. Their descriptions and schemas cost roughly 191 tokens of context every time the server is loaded.
Does the ONCE — Exactly-Once Reliability for AI Agent Actions MCP server require authentication?
No. We connected to ONCE — Exactly-Once Reliability for AI Agent Actions without credentials and it answered, so anything it exposes is reachable by anyone who knows the address.
Is the ONCE — Exactly-Once Reliability for AI Agent Actions MCP server still maintained?
ONCE — Exactly-Once Reliability for AI Agent Actions is still listed as active in the MCP registry. We last reached this channel on 4 October 2026. Those dates come from our own scans of the registry and the channel itself, not from anything the publisher announced.