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 real value beyond that: it enumerates the outcome states (for_sale, make_offer, not_found) and explains that not_found is scoped to a few marketplaces rather than a definitive negative, which aligns with and enriches openWorldHint=false.

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 the core purpose, followed by return states and the coverage caveat — all earning their place. The trailing 'Related: available, aged.' is a thin, unqualified dangling line that slightly dilutes the structure.

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 single-parameter read tool with an output schema, this is nearly complete: it explains outcome semantics and the coverage limitation so an agent will not over-interpret not_found. The remaining gap is sibling disambiguation against 'price' and 'market', which the description does not address.

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?

With schema description coverage at 100% and only one parameter, the schema already documents 'domain' including an example. The description adds no format, normalization, or TLD constraints beyond that, so the 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 ('Check whether a domain is listed for sale on a supported aftermarket... the asking price'), and names the related siblings available and aged. An agent can distinguish this from a general price or market tool without opening the 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?

The 'Related: available, aged.' line implies related tooling but gives no condition for choosing between them, and critically does not differentiate from the sibling tools literally named 'price' and 'market'. The coverage caveat ('not_found does not mean the domain is not for sale elsewhere') is useful interpretive guidance, but explicit when-to-use routing is absent.

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