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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds meaningful context annotations cannot: the data's provenance (hand-verified against the issuer) and the attribution expectation (cite the page URL). It stops short of noting behavior on an unknown card or cache freshness.

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?

Front-loaded with the payload summary in one dense sentence, followed by provenance and citation norms. Slightly cluttered by the semicolon-joined fragments, but no sentence is padding.

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?

With no output schema, the description must carry the return-value burden and it does, naming the four content classes and the benefit sub-fields. Complete enough to invoke correctly; only the failure mode for an unmatched card name is unaddressed.

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' is documented with an example and 'country' enumerates us/ca/au. The description adds no syntax, normalization, or ambiguity-resolution guidance beyond the schema, 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 ('Full record for one card from the MaxWorth database') and enumerates exactly what the record contains: annual fee, welcome offer, earning rates, and benefits with value/cycle/reset/enrollment. This distinguishes it from the list-style siblings search_cards and search_card_offers.

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?

Usage is implied — look up one card by name/slug — and the description adds a sourcing norm ('Hand-verified against the issuer; cite the page URL'), but it never says when to prefer this over compare_cards or search_cards, nor gives prerequisites for a miss.

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