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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds value beyond that by disclosing the result cap ('up to 10 matches') and the id handoff to `fetch`, though it says nothing about matching behavior (substring vs exact, fuzzy) or what happens when nothing is found.

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, zero filler. The purpose and supported games come first, then the return shape and the next-step call to `fetch`. Nothing is repeated from the title or annotations.

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?

An output schema exists, so return fields needn't be explained, and the description still volunteers the result limit and the id-to-`fetch` link, which is the key operational detail. The one missing piece is disambiguation from the nearly identical sibling `search_cards`, which matters for an 11-tool namespace with overlapping names.

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 parameter is documented as 'Card or sealed product name.', so the schema carries the load. The description reinforces the name-based query intent and the product-type scope, but adds no syntax, casing, or partial-match semantics beyond the schema — 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?

The description gives a specific verb ('look up') and resource ('trading cards or sealed products'), and enumerates the supported games, so the agent knows exactly what domain is searched. It falls short of a 5 because it never distinguishes this tool from the close sibling `search_cards`, leaving the agent unable to tell the two apart for card-only queries.

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?

It states the usage context ('by name') and prescribes the follow-up workflow by saying the returned ids should be passed to `fetch`, which is genuinely useful routing. However, with a sibling literally named `search_cards` in the same toolset, the absence of any when-to-use-this-vs-that guidance is a clear gap.

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