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

With no annotations, the description carries the full burden. It honestly discloses the scope boundary — what fields are included and explicitly what data categories are absent — which is the most important behavioral trait. However, it does not disclose the output format, how loose name matching behaves, or what happens when a card is not found, leaving gaps for a tool with zero annotation support.

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?

Two sentences with zero filler. The primary purpose is front-loaded in the first sentence, and the second sentence earns its place by setting explicit scope boundaries. Every clause contributes to correct tool selection.

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 one-parameter tool, the description is nearly complete: it states the operation, the cardinality, the fields compared, and the exclusions. The main gap is that no output schema exists and the return format is not described, but the implied side-by-side catalog-record output is reasonably inferable from the description and tool name.

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 description coverage is 100% (card_names with minItems/maxItems and 'matched loosely' is fully documented in the schema). The description's '2-5 cards' reinforces the schema bounds but adds no new meaning beyond what the input schema already provides, so the baseline of 3 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?

States a specific verb and resource ('same catalog record for 2-5 cards at once') with an explicit field scope ('comparing fees, networks and which benefits each carries'). The exclusion list ('no earning rates, welcome-offer amounts, transfer ratios, or bonus sizes') sharply differentiates it from siblings like estimate_point_value and find_transfer_routes.

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?

Provides an explicit when-to-use condition (2-5 cards needing comparison of fees/networks/benefits) and an explicit when-not-to-use via the exclusion list, which implicitly routes the agent to sibling tools for earning rates, transfer ratios, and bonus sizes. It stops short of naming the alternatives directly, so it doesn't earn a 5.

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