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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is fully covered. The description adds genuine behavioral context beyond those flags: prices are Stripe-verified, availability is live, and the response covers billing terms and delivery – all useful for interpreting the result.

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?

One sentence that front-loads the core purpose ('everything an agent can buy from Vigil') and then appends the qualifying details. Every phrase earns its place; there is no filler or repetition of the title.

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 zero-parameter, read-only catalog with annotations covering safety, the description tells the agent what to expect: the full product list, price verification, billing terms, delivery, and live availability. No output schema exists, and the description adequately fills that gap; nothing essential is missing for an agent to decide whether to call this tool.

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?

The input schema is empty, so there are no parameters to document and schema description coverage is trivially 100%. With zero parameters, the description is not obliged to explain inputs; it correctly focuses on the returned content, hitting the baseline of 4.

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 states a specific, actionable resource: everything an agent can buy from Vigil, with concrete fields (Stripe-verified prices, billing terms, delivery, live availability). This clearly distinguishes it from the sibling tools, which concern checkout (create_checkout, get_checkout) or page/document operations (read_page, search_pages, site_info).

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?

The description implies usage context – consult this catalog when the agent needs to know what can be purchased and its pricing or terms – but it never states an explicit when-to-use or when-not-to-use. There is no alternative named and no direct pointer to create_checkout for the actual purchase flow.

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