Surface Contract: platform API behavior and x402 pre-payment checks

Name: Surface Contract: platform API behavior and x402 pre-payment checks
Author: penny-surface-contract.penny-mcamp.workers.dev

by penny-surface-contract.penny-mcamp.workers.devversion 2026.10.22i★ –iRuns in the cloud

Registry namedev.workers.penny-mcamp.penny-surface-contract/surface-contract

How to install

What it does

Surface contracts: API behavior evidence, x402 pre-payment check, MCP server preflight

Connects Runs in the cloud
Account or key No key needed
Category Online shops & payments

Install

Pick the AI app you use, then copy the settings.

Passed 1/3 checks · What you ask goes through the maker’s server (penny-surface-contract.penny-mcamp.workers.dev) · ✓ Commands checked Nov 13, 2026

First: which AI do you use?

ClaudeWeb · app · phoneChatGPTWebClaude CodeTerminalCursorCode editorVS CodeCode editorOtherOther apps

Pick your app and the steps appear below.

Works with Claude · about 2 min

No key, nothing to install · Set it up once on claude.ai or the desktop app, then use it in chat · free accounts can add 1 · on Team/Enterprise an Owner adds it

Open Claude’s Connectors page
CustomizeConnectors
Done
Click “Add” → “Custom” → “Web” and fill in these 2 fields
Copy each value into the field with the same name in Claude, then click Continue
Name · NameSurface Contract: platform API behavior and x402 pre-payment checks
Remote MCP server URL · Addresshttps://penny-surface-contract.penny-mcamp.workers.dev/mcp
Click Continue past the sign-in settings Claude detected · under Authentication choose what the maker says (Sign in now, Sign in when needed or No sign in), then click Add
Done
Turn it on in a chat
+ConnectorsSurface Contract: platform API behavior and x402 pre-payment checks
Done
Try it
Use Surface Contract: platform API behavior and x402 pre-payment checks and tell me what you can do for me, then show me one thing
✓ If Claude says it is using Surface Contract: platform API behavior and x402 pre-payment checks or shows a Surface Contract: platform API behavior and x402 pre-payment checks tool in the answer, you are connected

Menu names checked against Anthropic’s help page on Nov 11, 2026 · your screen may differ slightly by app version

Works with ChatGPT, depending on your plan

Full MCP: ChatGPT Business, Enterprise or Edu on the web · Pro: connects with read/fetch permissions, so tools that change data may not work · Plus: not confirmed in OpenAI’s docs; if you see an add-custom-MCP option on the Plugins page you can try these steps · web only

Open ChatGPT’s add-MCP page on the web
Plugins+Add custom MCP server
Done
Fill in the name and address
Enter a name, paste the address under Connection, tick the risk warning and click Create as a plugin
Name · NameSurface Contract: platform API behavior and x402 pre-payment checks
Connection · Addresshttps://penny-surface-contract.penny-mcamp.workers.dev/mcp
Done
Pick Surface Contract: platform API behavior and x402 pre-payment checks in a chat
Start a new chat and pick Surface Contract: platform API behavior and x402 pre-payment checks from your plugins before typing
Done
Try it
Use Surface Contract: platform API behavior and x402 pre-payment checks and tell me what you can do for me, then show me one thing
✓ If ChatGPT says it is using Surface Contract: platform API behavior and x402 pre-payment checks or shows a Surface Contract: platform API behavior and x402 pre-payment checks tool in the answer, you are connected

Menu names checked against OpenAI’s help page on Nov 11, 2026 · your screen may differ slightly by app version

Works with Claude Code · about 2 min

No key, nothing to install

Open Terminal
Mac: press Command+Space and type Terminal · Windows: open PowerShell
Done

Paste this command and press Enter

claude mcp add --transport http --scope user surface-contract https://penny-surface-contract.penny-mcamp.workers.dev/mcp

Done

Type /mcp in Claude Code
You should see Surface Contract: platform API behavior and x402 pre-payment checks listed as connected
Done
Try it
Use Surface Contract: platform API behavior and x402 pre-payment checks and tell me what you can do for me, then show me one thing
✓ If Claude Code says it is using Surface Contract: platform API behavior and x402 pre-payment checks or shows a Surface Contract: platform API behavior and x402 pre-payment checks tool in the answer, you are connected

Menu names checked against Anthropic’s help page on Nov 11, 2026 · your screen may differ slightly by app version

Works with Cursor · about 2 min

No key, nothing to install

Click this button to open Cursor
Open in Cursor
Cursor asks you to confirm; click Install
Done
Open the AI chat in Cursor in Agent mode
Done
Try it
Use Surface Contract: platform API behavior and x402 pre-payment checks and tell me what you can do for me, then show me one thing
✓ If Cursor says it is using Surface Contract: platform API behavior and x402 pre-payment checks or shows a Surface Contract: platform API behavior and x402 pre-payment checks tool in the answer, you are connected

Menu names checked against Cursor’s help page on Nov 11, 2026 · your screen may differ slightly by app version

Works with VS Code · about 2 min

No key, nothing to install

Click this button to open VS Code
Open in VS Code
VS Code asks you to confirm; click Install
Done
Open the AI chat in VS Code in Agent mode
Done
Try it
Use Surface Contract: platform API behavior and x402 pre-payment checks and tell me what you can do for me, then show me one thing
✓ If VS Code says it is using Surface Contract: platform API behavior and x402 pre-payment checks or shows a Surface Contract: platform API behavior and x402 pre-payment checks tool in the answer, you are connected

Menu names checked against VS Code’s help page on Nov 11, 2026 · your screen may differ slightly by app version

Other apps that use MCP, such as Windsurf, Zed or Gemini CLI, each add servers differently. See how in the app list.

See every app that uses MCP →

Address for apps that connect over the web

Addresshttps://penny-surface-contract.penny-mcamp.workers.dev/mcp

JSON settings are under “For developers” below

Stuck? Ask people who use Surface Contract: platform API behavior and x402 pre-payment checks💬 Discussion →

For developers: Terminal commands and JSON settings

Over the web

Claude Code

claude mcp add --transport http --scope user surface-contract https://penny-surface-contract.penny-mcamp.workers.dev/mcp

Cursor (~/.cursor/mcp.json)

{
  "mcpServers": {
    "surface-contract": {
      "url": "https://penny-surface-contract.penny-mcamp.workers.dev/mcp"
    }
  }
}

VS Code (mcp.json)

{
  "servers": {
    "surface-contract": {
      "type": "http",
      "url": "https://penny-surface-contract.penny-mcamp.workers.dev/mcp"
    }
  }
}

These settings are generated from the maker’s registry entry. If the README says otherwise, follow the README.

At a glance

GitHub stars i: –
Downloads per weeki: Not on npm/PyPI
Verified domain: ✓ penny-surface-contract.penny-mcamp.workers.dev
Licence i: No licence stated
Connection: Runs in the cloud
Transport: streamable-http
Latest versioni: 2026.10.22
Categoryi: Online shops & payments
Published to registryi: Oct 22, 2026
Code last changedi: –
Maker: penny-surface-contract.penny-mcamp.workers.dev
Repo: –
Website: penny-surface-contract.penny-mcamp.workers.dev
Registry status: Active

Which apps can use it

Based on how this server connects and on each app’s own docs, checked Nov 10, 2026.

Connect over the internet in

Claude ChatGPT Goose LM Studio Msty Studio Cherry Studio Cursor VS Code + GitHub Copilot Visual Studio Windsurf (Devin Desktop)Zed Kiro Cline Continue JetBrains AI Assistant Claude Code Codex CLI Gemini CLI OpenCode nodecode Warp LibreChat Open WebUI Raycast

All apps, with pros and cons →

What it can do

Tool names and descriptions exactly as the server reported them on Nov 12, 2026. The maker wrote them, not us; we show them as plain text.

list_surface_contracts
List the platform surface contracts published in Penny's free registry, with claim counts.
get_surface_contract
Get the machine-readable surface contract for a platform host (read/write semantics, pending states, rate limits, limits, idempotency, pagination completeness, data portability), each claim carrying its evidence and its verification status.
verify_surface
Run the anonymous conformance checks for a contract now and return verified / failed / unknown / manual / unsupported per claim.
contribute_discrepancy
Report a platform behaviour that contradicts a published claim, or a new claim, with evidence. One-line call: POST /v1/contribute with {contractId, kind, statement, evidence[], reporter, observedAt}. Stored as pending; a published contract is never changed without independent ver
get_integration_recipe
Get a plain-text integration recipe for a platform: the order of operations to use it, and a guard clause for every behaviour we measured going wrong, each naming the contract claim behind it. Derived from the contract, so it cannot drift from it.
preflight_mcp_server Looks like an instruction to the AI
Run the anonymous MCP handshake against ANY https MCP endpoint you name, right now, and get back a verdict (open / refused / unreachable / initialize-transport-error), the shape of any refusal body, whether the server is stateful (sets Mcp-Session-Id), how many tools tools/list r
prepay_check
Check an x402 route BEFORE you pay it. GET /v1/prepay?url= makes ONE unpaid GET with no payment header and no credential, and returns one row: the measured HTTP status, the parsed x402 v2 challenge (scheme / network / asset / amount / payTo), whether that challenge is schema-vali

Basic checksi

We check information anyone can see; we have not read the code. Checks that do not apply are left out of the count. · Checked Nov 13, 2026

! Caution
Maker matches the repo
The registry lists no source repo, so we cannot match the publisher (penny-surface-contract.penny-mcamp.workers.dev) to the code
… Not checked yet
Still maintained
We have not read this repo from GitHub yet
… Not checked yet
Has a licence
We have not read this repo from GitHub yet
✓ Pass
Endpoint responds
Responded in 812 ms (HTTP 200)
– Not applicable
Sign-in with OAuth
No sign-in needed
✕ Fail
No hidden instructions in tool descriptions
1 tool descriptions contain text that looks like instructions to the AI. Read them below before installing

Discussion

Ask, share a tip or report that it does not work. Sorted by what people marked helpful.

No posts yet. Be the first to ask or share.

Posts here are written by users, not the PopNx team.

User reviews

No reviews yet

Compared with others in Online shops & paymentsi

More stars than 0% of the other 2770 servers in this category
Published to the registry more recently than 60% of the other 2770 servers in this category
Basic checks equal to or better than 12% of the other 2770 servers in this category

Compared with every active server in this category in the registry. Stars count only when the publisher owns the repo.

Common questions

Is Surface Contract: platform API behavior and x402 pre-payment checks safe?

It passed 1 of 3 applicable basic checks. We have not read the code. Before adding a key or token, see what access the server asks for and use a key with only the permissions you need.

What keys or codes does it need?

The registry does not list a required key, though some servers ask you to sign in on first use.

Does it run on my computer or in the cloud?

It runs in the maker’s cloud. Connect over the internet with nothing to install, but what you send passes through the maker’s servers.

Is it still maintained?

The GitHub repo last changed –, and the latest version (2026.10.22) reached the registry 22 days ago.

Which apps can use it?

Apps that support MCP, such as Claude Desktop, Claude Code, Cursor and VS Code. It connects by URL, so apps that accept remote MCP servers work too, such as ChatGPT on the web (full MCP on Business and above; Pro read-only).

What can I use instead?

In the same category: Spree Commerce developer docs for AI agents, Stripe MCP, Sessy — Amazon SES observability

Others in the same category

Servers in the same category from other makers, sorted by stars.

Reading a card:↓ Downloads per weeki★ GitHub starsiThree pillars: reviews · checks · usageiUpdated = latest version published to the registryi

Spree Commerce developer docs for AI agents

Spree Commerce docs for AI coding agents: build headless B2B and marketplace ecommerce on its APIs.

by spreeWidely used★ 15.8K Stars for the whole repoUpdated 14 days ago

Runs in the cloud

How to connect

Stripe MCP

Stripe’s official server lets AI view and manage customers, products, payments and invoices. Connect to Stripe’s cloud and sign in with OAuth.

by stripeWidely used★ 2.1KUpdated 13 months ago

Runs in the cloud✓ service owner · stripe.com

How to connect

Sessy — Amazon SES observability

Read-only Amazon SES observability: search events, inspect bounces, pull delivery stats.

by marckohlbruggeGrowing★ 945Updated 3 months ago

Runs in the cloud

How to connect

README from the maker

No README found in the repo

Surface Contract: platform API behavior and x402 pre-payment checks

What it does

Install

Open Claude’s Connectors page

Click “Add” → “Custom” → “Web” and fill in these 2 fields

Turn it on in a chat

Try it

Open ChatGPT’s add-MCP page on the web

Fill in the name and address

Pick Surface Contract: platform API behavior and x402 pre-payment checks in a chat

Try it

Open Terminal

Paste this command and press Enter

Type /mcp in Claude Code

Try it

Click this button to open Cursor

Open the AI chat in Cursor in Agent mode

Try it

Click this button to open VS Code

Open the AI chat in VS Code in Agent mode

Try it

Over the web

At a glance

Which apps can use it

Related guides

What it can do

Basic checksi

Maker matches the repo

Still maintained

Has a licence

Endpoint responds

Sign-in with OAuth

No hidden instructions in tool descriptions

Discussion

User reviews

Compared with others in Online shops & paymentsi

Common questions

Others in the same category

Spree Commerce developer docs for AI agents

Stripe MCP

Sessy — Amazon SES observability

README from the maker