buy_creditsCreates a secure Stripe checkout link for a pack of non-expiring verification credits. Packs: 1 for $10.00, 5 for $30.00, 10 for $50.00. Give the user the link to pay; credits are added once payment completes.
| Name | Required | Description | Default |
|---|---|---|---|
| quantity | Yes | Number of credits: 1, 5, 10 |
Changes observed during successful MCP inspections.
Input schema / properties / quantity / descriptionPrevious value: -"Number of credits: 1, 3, 5, 10, 25, 50"New value: +"Number of credits: 1, 5, 10"Input schema / properties / quantity / enumPrevious value: -[
- 1,
- 3,
- 5,
- 10,
- 25,
- 50
-]New value: +[
+ 1,
+ 5,
+ 10
+]Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already flag this as a non-read-only, open-world operation, and the description adds real behavioral context beyond them: the call returns a link rather than performing the purchase, credits are non-expiring, and fulfillment is asynchronous ('added once payment completes'). It omits auth/permission requirements and whether the link expires, keeping it below a 5.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Three short sentences, front-loaded with the action and result, then pricing, then the follow-up instruction. Every sentence carries distinct information with no redundancy.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a single-parameter tool with no output schema, the description supplies the missing return-value semantics (a checkout link), the fulfillment timing, and pricing. Nothing an agent needs in order to invoke and then act on the result is absent.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100% with an enum already listing 1/5/10, so the baseline is 3. The description does add the price mapping ($10/$30/$50) that the schema lacks, which is mildly useful for pack selection, but adds no format or constraint detail for the single quantity parameter.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
States a specific verb and resource — 'Creates a secure Stripe checkout link for a pack of non-expiring verification credits' — which is unmistakably distinct from every sibling tool (verification requests, calculators, account/report reads). An agent can identify the tool's function without consulting the schema.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description gives the operative usage flow: obtain the link, hand it to the user, and credits land only after payment completes. It also enumerates the purchasable packs. It stops short of explicit exclusions (e.g., what to do if the user wants a custom quantity, or alternatives to Stripe), so it is clear context rather than full when/when-not guidance.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Add one secure layer between your agents and this server.