list_domains

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds one behavioral fact beyond them — that the returned count is deterministic — but says nothing about result volume, pagination, or ordering.

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?

Two compact clauses, front-loaded with the primary action and with zero filler. The trailing 'Returns deterministic count' is slightly cryptic but does carry information, so no sentence is wasted.

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?

An output schema exists, so return values need not be described, and the safety profile is covered by annotations. For a simple single-parameter list tool the description is nearly sufficient, with only filtering scope and any result limits left unstated.

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 0% and the single 'query' parameter carries no description, so the description must compensate. 'optional substring search' does meaningfully clarify that query is a substring match rather than an exact-name filter and that it is optional, which is real added meaning over the bare schema.

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 ('List account domains') and adds the scope of the listing plus the search capability. It is distinguishable from the singular get_domain sibling by the plural resource, but it never explicitly contrasts itself with the other list-style siblings (list_dns_records, list_forwards, list_invoices).

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?

'optional substring search' implies that the query parameter exists for filtering and that calling without it returns the full list, so usage is inferable. However, there is no explicit when-to-use vs. alternative (e.g. get_domain for a single domain) and no note on result limits or paging.

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