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

Annotations already declare readOnlyHint=true, openWorldHint=true, and destructiveHint=false, so the safety profile is covered. The description adds useful behavioral context by stating that the tool returns available names across TLDs and that buying/connecting are separate follow-up actions, giving the agent a clearer model of what this call does and what it does not do.

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, each earning its place: the first states the core action and example, the second describes the return value and buy path, and the third covers the connect alternative. It is front-loaded and free of 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 an output schema present, the return value is already documented, and the description covers purpose, follow-up actions, and alternatives. The annotations handle safety and open-world behavior, and the schema covers parameters, so nothing necessary for correct invocation or selection is missing.

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%, and the schema already documents query, context, and tlds with examples. The description reinforces that query is a base name and that availability is checked across TLDs, but it does not add meaning beyond what the schema already provides. Baseline 3 is appropriate.

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 verb ('Search'), a clear resource ('available domains'), and the output ('available names across TLDs'), with a concrete example ('mybakery'). It also distinguishes itself from sibling tools by naming buy_domain and connect_domain, so an agent can immediately tell what search_domains does and does not do.

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 explicitly routes to alternatives: 'To buy one, call buy_domain' and 'Use connect_domain for a domain the user already owns.' This gives clear when-to-use versus when-to-use-another guidance, leaving no ambiguity about the choice between searching, buying, and connecting.

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