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

Annotations already declare readOnly, openWorld, idempotent, and non-destructive hints, so the description only needs to add value beyond those. It adds important behavioral context: the tool costs 0.01 USDC via x402 and produces an estimate based on matched supply, price premium, release age, limited-edition metadata, and rerelease information. It does not detail output shape, but the presence of an output schema lowers that burden.

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?

The description is three concise sentences with no filler. It front-loads the core action, then the price, then the usage triggers. Every sentence adds useful information for selecting and invoking the tool.

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 tool with an output schema, safety annotations, and a short input schema, the description is nearly complete. It communicates cost, methodology, and clear invocation triggers. The only minor gap is that it does not explicitly say when to prefer a sibling tool such as anime_authenticity or anime_market, though the usage list makes the boundary reasonably clear.

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?

The schema already describes 'query' and 'id', and 'lang' is a self-explanatory enum with a default. With schema description coverage at 67%, the description does not need to repeat parameter details. It mentions high-level inputs (supply, premium, age, metadata) but does not map them directly to parameters, which is acceptable given schema coverage.

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 states a specific action ('Estimate scarcity and rerelease risk') on a specific resource ('Japanese anime collectible') and lists the signals used. It also clearly frames the intended user questions ('rare, hard to find, limited, likely to appreciate, or exposed to rerelease risk'), which helps distinguish it from sibling tools like anime_authenticity or anime_market.

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?

The description gives an explicit 'Use when the user asks whether...' list, covering the main cases where this tool should be chosen. It does not name alternative sibling tools or provide when-not-to-use guidance, but the usage trigger is specific enough for an agent to route correctly in most cases.

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