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

Annotations already declare read-only, idempotent, closed-world, non-destructive, but the description adds real behavioral context: it reads the published snapshot behind /stores/<host>, performs no store fetch, scan, or login, and is advisory because ARC stops before payment. It also documents the error envelope shape ({error:{code, message, next_step}}), which annotations cannot convey.

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?

It is front-loaded with the when-to-call clause, then return fields, then an example, then constraints and error shape — every element is useful. Some phrasing is dense and domain-specific ("ARC", "verdict", "citable store page"), but no sentence is 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, the description does the work of naming return fields (verdict, checked_at, category, fix, page/JSON/Markdown links) and the error shape, which is adequate for a one-parameter read. The one gap is the set of possible verdict/category values, which an agent would need to interpret results.

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% and the single parameter already documents "Store domain or URL, such as allbirds.com." The description's example call repeats the same format without adding syntax rules (e.g., whether a full URL with path is normalized). Baseline 3 applies when the schema carries the semantics.

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 uses a specific verb and resource: it returns the store page's verdict, checked_at, category, the recorded fix, and links to the page plus its JSON and Markdown. An agent can tell this is a read of a published store snapshot rather than a scan. It never names the closest sibling (store_card) to say how they differ, so differentiation is left implicit.

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?

"Call this when a user asks what ARC recorded for a store, or you need the citable store page" gives a concrete trigger, and "Saved checks only: no store fetch, no scan, no login" excludes the live-check path without naming which sibling to use instead. The negative guidance is strong; explicit routing to precheck/before_checkout for fresh checks is missing.

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