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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The one piece of added behavioral value is the mention that each card reports when its data was last verified, signalling staleness; there is no ordering, pagination, or 'what happens if the wallet is empty' information.

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?

One front-loaded sentence with the verb first and the field list after, no filler. The list of eight included data points is long but each item conveys distinct content the caller would otherwise have to infer from the output schema.

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 parameters, safety annotations present, and an output schema exists, so the description need not explain return values. It nevertheless confirms scope and freshness metadata, making it sufficient; only the lack of sibling routing keeps it from the top.

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 nothing for the description to disambiguate. Baseline 4 applies.

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?

A specific verb and resource ('Lists the user's cards') with an enumeration of the wallet fields returned, so the agent knows this is a full wallet snapshot. It never distinguishes itself from siblings like search_cards or cheat_sheet, but the scope (all cards, all fields) is 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?

No explicit when-to-use or when-not statement and no named alternative. The field enumeration implies the intended use (when the agent needs caps, rewards value, welcome-bonus progress, or data freshness for all cards at once), but that inference is left to the reader.

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