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

Annotations already establish readOnlyHint and openWorldHint, yet the description adds material context beyond them: per-call pricing ($0.002 USDC via x402 across three chains), the fact that failed calls are not charged, page size, and sort order. Only the payment/auth mechanics of x402 are left implicit.

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?

A single dense paragraph that front-loads what data is returned before moving to filtering, pagination, and pricing. It is long but nearly every clause carries operational information; only the parenthetical sub-rating list could be trimmed.

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, return-value detail is technically redundant, but the description covers scope, filtering, paging, ordering, and cost, which is everything needed to invoke it correctly. The only gap is how x402 payment is actually presented on a call.

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 the baseline would be 3, but the description adds meaning the schema lacks: it clarifies that level/type filter the result set and that page size is fixed at 25. It also implies state+city form the geographic scope of the query.

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?

Starts with a specific verb-and-resource statement ('US schools in a city from GreatSchools') and then enumerates the exact fields returned. An agent can instantly tell this retrieves school directory/rating data, which nothing else in the sibling list does.

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?

Explains that results can be filtered by level and type and are paginated 25 at a time, best-rated first, which gives clear calling context. It does not name exclusions or alternatives, but no sibling tool overlaps in this domain, so there is little to disambiguate.

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