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 real value beyond that by specifying the payload contents and, importantly, that every row carries its grade, check date and source — provenance an agent would otherwise have to discover empirically. It does not mention error behavior for an unmatched slug, which keeps it from a 5.

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 summary clause, then a dense but purposeful enumeration that maps to the actual payload. It is one long sentence and the list is heavy, but each item earns its place by telling the agent what fields come back. No filler or restatement of the title.

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 carries the return-value burden and does so by enumerating the record categories plus the provenance columns. Missing only edge behavior — unknown slug handling and any pagination or size caveat — which is minor for a single-record read behind full annotation coverage.

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 coverage is 100% and the single slug parameter is fully documented with pattern, length bounds and a concrete example. The description adds no further meaning about the slug (e.g. case sensitivity, aliasing, or what to do on miss), so the baseline 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 resource and scope: 'Everything on record for one card,' then enumerates the record types (fees, earn rules, rail, exclusions, partners, lounges, milestones, statuses, change history). An agent can tell this is the single-card deep-detail fetch rather than a list/search. It stops short of naming a sibling, so the contrast with search_cards is only implied by 'one card.'

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 rather than stated: the slug parameter description says the value comes 'from search_cards,' which signals the search-then-fetch flow. There is no explicit when-to-use/when-not guidance and no statement of what happens if the slug is unknown or stale.

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