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

With no annotations provided, the description carries the full burden, and it does well: it explains that the tool prepares an unsigned payload rather than executing a transaction, and that a buyer wallet signature is required. This gives the agent important behavioral context beyond the plain 'buy' action.

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 sentences with no filler. The core action is front-loaded, and the important signature requirement is stated immediately after. Every word contributes to the tool's meaning.

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 tool with no output schema and no annotations, the description adequately explains the output concept an unsigned transaction payload and the necessary signature step. It could add more detail about return structure or failure conditions, but the description is sufficient for an agent to understand and invoke the tool correctly.

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 already describes all three parameters with 100% coverage, so the baseline is 3. The description adds general context like 'ETH value' and 'buyer wallet signature,' but it does not add substantial parameter-specific meaning beyond what the schema already provides.

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 names a specific action and resource: preparing an unsigned payable transaction payload to purchase an actively listed .i domain from the marketplace contract. This clearly distinguishes it from siblings like marketplace_make_offer, marketplace_accept_offer, and marketplace_list_domain.

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 gives clear context for when to use the tool: when purchasing an actively listed .i domain directly from the marketplace. It also calls out a key prerequisite, the buyer wallet signature, which helps the agent understand the workflow. It does not explicitly exclude alternatives like making an offer, but the active-listing purchase context is reasonably explicit.

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