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

Annotations only say readOnlyHint and openWorldHint; the description adds substantive behavior the annotations cannot: data comes from faire.com through a residential proxy, wholesale prices are excluded, and each successful call costs $0.02 USDC via x402 (Base/Solana/Arc) with failed calls uncharged. Cost and data-completeness caveats are exactly what an agent needs before committing to a paid call.

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 purpose, then scope limitation, then cost — a sensible order. It is one very dense sentence enumerating returned fields, which partly duplicates the existing output schema, but every clause (login restriction, proxy source, charge model) carries information.

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, the description need not explain return values, and it still covers the two things structured fields cannot: the logged-out data limitation and the x402 billing model with failure handling. For a one-parameter, read-only tool that is complete.

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% and the single `category` parameter already documents the format (faire.com/category/<name>) with examples; the description adds no syntax or normalization advice beyond that. Baseline 3 is appropriate since the schema does all the parameter work.

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 (Faire wholesale marketplace category listing) plus the exact scope ('logged-out view') and enumerates the returned fields: product token, brand, suggested retail price, case quantity, stock, ratings, flags, image and link. An agent can immediately tell this is a Faire category browse, not a product search or price-comparison tool.

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: read it as 'fetch listings for a given Faire category'. There are no explicit when-to-use/when-not rules and no sibling alternatives named, though the note that wholesale prices require a retailer login effectively warns an agent not to use it for wholesale pricing. That single exclusion is real value but far from full routing guidance.

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