A card's verified rates

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description must fully disclose behavioral traits. It lists the fields returned but does not mention whether the operation is read-only, requires authentication, can return errors (e.g., for invalid IDs), or has any side effects. It is safe to assume it's a retrieval, but the description does not explicitly state this or any edge-case behaviors, leaving the agent without guidance on failure handling.

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, information-dense sentence that front-loads the core scope ('Everything RightCard knows about one card') before enumerating the data types. There is no filler or redundancy. While slightly long, it is appropriately detailed for a tool that returns a rich object.

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 simple lookup with one parameter and no output schema, the description lists the key data points an agent might need, which is helpful. However, it omits how to specify which card (the 'id' parameter is not explained), any error conditions, or the result's structure. It is adequate for understanding what data is returned but incomplete for guiding the call correctly.

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 input schema has a single required parameter 'id' with no description (0% coverage). The tool description never mentions 'id' or clarifies what it represents (e.g., a card identifier). The phrase 'one card' implies the parameter identifies the card, but this is not explicit. The description adds no meaning to the parameter beyond the schema's bare existence, and since schema coverage is 0%, it fails to compensate.

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 states that the tool returns comprehensive information about a single card, listing specific data points (rates by category, base rate, currency, annual fee, verification status, rotating windows, and the choose-your-category spec). This distinguishes it from sibling tools like search_cards (search) and best_card (recommendation), though it does not explicitly name alternatives. The verb is implied as 'retrieve' but the resource and scope are unambiguous.

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?

There is no guidance on when to use this tool versus siblings. The description does not mention prerequisites, such as having a card ID, nor does it contrast with search_cards or best_card. An agent must infer that this is for fetching details of a known card, which is not stated explicitly. No exclusions or conditional logic are provided.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.