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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds real behavioral context beyond that: grading/authentication metadata (including the PSA cert link) is disclosed only conditionally, when the card is held in Fanatics' vault, which tells the agent to expect missing fields rather than treat them as an error.

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 purpose in the opening clause, then the return contents. It is one dense sentence and the long field enumeration is informative rather than filler, though it runs slightly long for what it conveys.

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 an output schema present and full schema coverage on both params, the definition has what an agent needs to call it correctly; the returned-field list is arguably redundant with the output schema. The main omission is the absence of any routing guidance to search/sold-item siblings.

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%, so the id UUID format and the WEEKLY/PREMIER type parameter are already documented in the schema. The description enumerates listing types but never ties them back to the 'type' parameter or explains its default, so it adds no meaning beyond the schema. 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 verb+resource ('listing detail') and scopes it across the three listing categories handled (weekly-auction, premier-auction, fixed-price/Instant Rips), which distinguishes it from siblings like fanaticscollect_search or fanaticscollect_auctions. An agent can tell this is a single-listing lookup rather than a search without opening the 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?

Usage is only implied: the required 'id' makes it obvious you call this to hydrate one listing, but the description never says when to prefer this over fanaticscollect_search, fanaticscollect_sold_items, or fanaticscollect_auctions, nor where the id comes from. Adequate but leaves routing to inference.

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