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

Goes well past the readOnly/openWorld annotations: discloses the data source (newegg.com public search page via a residential proxy), pagination behavior (~36-42 items per page, pages 1-20), that a total result count is returned, and the exact billing model ($0.002 USDC per successful call via x402 on Base/Solana/Arc, failures not charged). The cost/auth detail is exactly the kind of context annotations cannot carry.

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 and return fields, then alternatives, then pricing — a sensible order with no filler sentences. The long comma-separated field list is dense but each item is a genuine return field, so it earns its space; the paragraph is slightly run-on.

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 two-parameter search tool with an output schema and annotations, nothing an agent needs to call it correctly is missing: source, scope (US), pagination limits, result count, cost and payment rails are all stated. Return-value detail is a bonus rather than a substitute for the output schema.

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%, so both parameters (q, page) are already documented, and the description's 'page 1 to 20' merely repeats the schema constraint. The one added nugget is 'about 36-42 items per page', which lets an agent reason about how many pages to fetch, but that is marginal value over the schema.

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 ('Newegg (US) product search') and enumerates exactly what the search returns (item number, title, model, price, rebate, stock flag, ratings, rank, etc.). It also explicitly names the sibling sites it is NOT (uline, aliexpress), so an agent can route without opening a 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?

Explicitly routes the agent: 'ecommerce_uline when you need Uline industrial supply product by item number; ecommerce_aliexpress when you need AliExpress product search.' That gives clear positive selection criteria against two close siblings. It stops short of stating when NOT to use it (e.g. non-US Newegg, non-product queries) or any query-shaping advice.

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