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

Annotations already declare readOnly, idempotent, non-destructive and non-openWorld, so the safety profile is covered. The description adds genuine behavior beyond that: an iterative fill-in-the-gaps flow and the contents of the returned brief (calculation accuracy, form behavior, search visibility, performance, privacy rules).

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?

Three sentences, front-loaded with the core purpose, then the interaction model, then the alternate mode. Slightly dense in the final sentence but every clause conveys distinct information with no filler.

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 no output schema present, the description must describe the return value, and it does: missing-details list followed by the brief with its rule categories. Combined with 100% schema coverage on 13 parameters, the definition is nearly self-sufficient; only the omission of truncation/response-size behavior (left to the maxTokens schema field) keeps it off a 5.

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% across all 13 parameters, so the schema already carries the parameter documentation. The description reinforces only the `format` enum meaning ('page-family' returns a brief for a family of pages built from dataset rows), which the schema also states. 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?

States a specific verb and resource: 'Returns a build brief for an interactive widget on an article or landing page', and enumerates what the brief contains. The resource is unambiguous against sibling guide tools (get-jig-guide, get-motion-guide), but the description never explicitly distinguishes itself from those siblings.

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?

Gives clear invocation context: 'Pass what is known about the widget', implying partial input is acceptable, and the response tells the caller what is still missing. The page-family mode is scoped with a concrete example. No explicit when-not-to-use or named alternatives are given.

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