cardRetrieve a card's rates by category, base rate, annual fee, currency, verification status, rotating bonus windows, and choose-your-category spec to inform credit card recommendations.
Everything RightCard knows about one card: rates by category, base rate, currency, annual fee, verification status, live rotating windows, and the choose-your-category spec if it has one.
| Name | Required | Description | Default |
|---|---|---|---|
| id | Yes |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the burden. It transparently lists the returned content categories, which helps set expectations, but it doesn't disclose what happens for unknown card IDs, whether the data is read-only, or how verification/live windows behave. It's reasonable but not fully transparent.
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?
The description is a single, well-structured sentence with a clear subject and a colon-delimited list of covered data points. It front-loads the core purpose and wastes no words, though the list is somewhat long.
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 one-parameter lookup tool with no output schema, the description covers the main information an agent needs: the input is a card id and the output is the full card knowledge. The lack of usage guidance and handling of edge cases prevents a perfect score, but the core invocation context is clear.
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 schema has a single id parameter with no description (0% coverage), so the description must compensate. It implies id identifies a card ('about one card'), but it doesn't clarify the id format, source, or behavior for invalid ids. The description adds minimal meaning beyond the schema.
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?
The description clearly identifies the resource (one card) and the tool's purpose: returning all known card data including rates, fees, and rotating windows. It doesn't explicitly distinguish itself from siblings like best_card or search_cards, but its focus on a single card's full data profile is sufficiently distinct for an agent to infer its role.
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 no guidance on when to use this tool versus its siblings. It doesn't mention search_cards for finding cards, best_card for ranking cards, or rotating_calendar for rotating windows, leaving the agent to infer the appropriate context from the resource name alone.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.