Test Card Generator Skill
The tool
Let your agent mint valid test card numbers. Call it as an MCP tool to generate Visa, Mastercard, Amex and more for payment testing.
Once your client is connected to the VerveKit MCP server, this appears in its tool list as TestCardGeneratorSkill. It is read-only and open-world: it fetches, it never mutates anything on your side, so most clients will call it without asking you to confirm.
{
"name": "TestCardGeneratorSkill",
"arguments": {
"brand": "visa"
}
}What that looks like in a conversation
You don't name the tool — the model picks it. Asking about visa in the terms this source covers is enough for it to reach for TestCardGeneratorSkill on its own.
Connecting
One server URL covers every skill in the catalog, including this one. Authorization is OAuth — the client opens a browser once and there is no key to paste into a config file.
{
"mcpServers": {
"vervekit": {
"url": "https://api.vervekit.com/v1/mcp"
}
}
}https://api.vervekit.com/v1/mcpPer-client setup — Claude Desktop, Cursor, VS Code, ChatGPT — is on the MCP setup page.
Arguments
These are the properties on the tool's inputSchema, so a well-behaved client validates them before the call is made.
| Argument | Type | Example | Description |
|---|---|---|---|
brandRequired | string | visa | The brand of the card to generate One of: visa, mastercard, amex, discover, jcb, diners, unionpay. |
countPremium | integer | 5 | The number of test card numbers to generate |
includeAvatarPremium | boolean | true | Include an AI-generated face avatar for the card owner |
What the model gets back
The result carries a structuredContent object matching the tool's declared outputSchema, so a client can read fields without parsing prose. status is "ok" on success and error is null; a null field means the value wasn't available for that input, not that the call failed.
{
"status": "ok",
"error": null,
"data": {
"brand": "visa",
"count": 5,
"cards": [
{
"cvv": 175,
"issuer": "SOUTHEAST F.C.U.",
"id": "0faca124-9a33-4ac6-a3df-8bf103025779",
"number": "4750377207233152",
"expiration": "12/2030",
"brand": "visa",
"number_alt": {
"masked": "************3152",
"unmasked": "4750 3772 0723 3152",
"last4": "3152"
}
},
{
"cvv": 129,
"issuer": "U.S. BANK, N.A.",
"id": "0d074efe-69e2-4e30-b49a-4cead1ea8411",
"number": "4431387818727358",
"expiration": "12/2030",
"brand": "visa",
"number_alt": {
"masked": "************7358",
"unmasked": "4431 3878 1872 7358",
"last4": "7358"
}
},
{
"cvv": 249,
"issuer": "AUGUSTA VAH F.C.U.",
"id": "2f01f458-7422-400e-bbcf-41364564193b",
"number": "4425919427248836",
"expiration": "12/2030",
"brand": "visa",
"number_alt": {
"masked": "************8836",
"unmasked": "4425 9194 2724 8836",
"last4": "8836"
}
},
{
"cvv": 892,
"issuer": "CITIZENS SECURITY BANK AND TRUST COMPANY",
"id": "d311e9d0-f410-4f75-a21f-f14125c88cbb",
"number": "4127737519045634",
"expiration": "12/2030",
"brand": "visa",
"number_alt": {
"masked": "************5634",
"unmasked": "4127 7375 1904 5634",
"last4": "5634"
}
},
{Fields
| Field | Type | Example | Description |
|---|---|---|---|
brand | string | visa | Card brand for generated test cards |
count | number | 5 | Total number of generated test cards |
cards | array[5] | list of rows | Array of generated test card objects with details |
cards.0.cvv | number | 175 | |
cards.0.issuer | string | SOUTHEAST F.C.U. | |
cards.0.id | string | 0faca124-9a33-4ac6-a3df-8bf103025779 | |
cards.0.number | string | 4750377207233152 | |
cards.0.expiration | string | 12/2030 | |
cards.0.brand | string | visa | Card brand for generated test cards |
cards.0.number_alt | object | {…} | |
cards.0.number_alt.masked | string | ************3152 | |
cards.0.number_alt.unmasked | string | 4750 3772 0723 3152 | |
cards.0.number_alt.last4 | string | 3152 | |
ownerPremium | object | {…} | Cardholder owner information and address details |
owner.name | string | Benny Swaniawski | Full name of the card owner |
owner.address | object | {…} | |
owner.address.street | string | 007 Nelson Mountains | Street address of card owner |
owner.address.city | string | Margueriteton | City of card owner residence |
owner.address.state | string | Washington | State of card owner residence |
owner.address.zipCode | string | 39956-7950 | Postal zip code of card owner |
owner.avatarPremium | string | https://storage.googleapis.com/apiverve/APIResources/faces/Male/30-40/12345678.jpg?X-Goog-Signature=... | URL to AI-generated face avatar image |
Failure modes
Errors come back as tool errors with a sentence the model can act on, not a bare status code.
| Status | What it means |
|---|---|
400 / 422 | The arguments didn't validate. The message names the offending one. |
401 | The OAuth session is invalid or expired — reconnect the server. |
403 | Out of credits. Not a bad key — the month's allowance is spent. |
404 | This skill isn't part of VerveKit. Check the catalog. |
429 | Brief rate limit. Retrying after a moment succeeds. |
Other ways to use Test Card Generator Skill
Set up Test Card Generator Skill on VerveKit, or reach the same source a different way. Your VerveKit account and credits work on all of them — one key, one balance.
Frequently asked questions
Do I have to tell the agent to use TestCardGeneratorSkill?
No. The tool's name and description are in the model's context once the server is connected, so it selects the tool when the question calls for it. Naming it explicitly works too and is useful when you want to force the call.
Does connecting the server expose every tool at once?
Yes — one connection lists the whole VerveKit catalog. Clients with a tool budget can usually filter the list; the credit cost is per call, so an unused tool costs nothing.
What does a call cost?
1 credit each time the tool actually runs. A model that reasons about the tool without calling it costs nothing.
Is there a REST version of this?
Yes — the same source is available as a plain HTTPS endpoint on APIVerve, linked above. Same data, same credits, same account.