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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the description is free to add operational context: result cap of 5, the raw vs PSA 10 price fields, the card_id, the page link, and the API key requirement. It does not describe pagination or behavior when no match is found, but the added auth and result-shape context is substantial.

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?

Purpose is front-loaded in the first sentence, with examples, sibling routing, return shape, and auth needs following in order. The three inline examples cost some length but directly serve query construction, so they earn their place.

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 search tool with a full output schema, the description covers everything an agent needs: what it finds, how to phrase the query, the result cap, sibling routing, and the API key prerequisite. Return values need not be restated, and nothing material is missing.

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 67%; the schema documents query and category, but the description adds real meaning by prescribing the collector-style phrasing and giving three worked examples, and it explains the practical effect of limit ('up to 5 matching cards'). category is left to the schema, which is acceptable given its inline description.

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 ('Find a sports or trading card and its current sold price') and explicitly separates itself from the sibling tool by noting get_card_prices handles all grades of one card. An agent can distinguish the two without opening either schema.

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?

Names the alternative (get_card_prices) and the condition that selects it ('for every grade of one card'), and instructs how to phrase the query as a collector would with concrete examples. It also states the prerequisite of a HobbyCardIndex API key.

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