Retrieve saved payment methods, returning only card brand, last 4 digits, and cardholder name so checkout forms can be filled without exposing full card numbers or CVV.
List saved payment methods. Returns card brand, last 4 digits, and cardholder name only -- full card numbers and CVV are never included. Use use_payment_method to fill a checkout form.
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral burden and does disclose a meaningful trait: only masked fields (brand, last 4, cardholder name) are returned and full numbers/CVV are never included. It does not mention auth requirements, session scoping, or behavior when no methods are saved, so it falls short of 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, each earning its place: purpose, return contract, and next-step routing. The most important information (what is listed and what is masked) is front-loaded.
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?
No output schema exists, so the description must and does describe the return fields. For a zero-parameter read tool with no annotations, this covers everything an agent needs to call it correctly and interpret the result.
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?
The tool takes zero parameters, so there is no parameter semantics to convey; the baseline for a no-parameter tool is 4.
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 ('List saved payment methods') and immediately specifies what the result contains, which distinguishes it from the adjacent use_payment_method tool. An agent can tell exactly what this tool returns without opening a 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?
Explicitly routes the agent to the sibling tool for the downstream action: 'Use use_payment_method to fill a checkout form.' This gives clear context for where this tool fits, though it does not state exclusions (e.g., when not to call it) or prerequisites such as an active session or authenticated context.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.