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

Goes well past readOnlyHint=true by disclosing quota consumption ('costs write points'), registry latency, a 25-second timeout, and the meaning of 'unknown' (registry did not answer; retry later). The phrase 'costs write points' is slightly at odds in tone with readOnlyHint=true, but it reads as quota/billing rather than data mutation, so no true contradiction.

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?

Four tightly packed clauses, front-loaded with the outcome and followed by format rule, status enum, and cost/latency caveat. No waste, though the telegraphic 'Costs write points: the registry is slow' is compressed to the point of ambiguity.

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 one parameter, an output schema, and readOnlyHint already covering the safety profile, the description supplies the remaining essentials: query interpretation, the status vocabulary, and timeout/cost expectations. Missing only the recommended follow-up when a domain comes back 'available' or 'unknown'.

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 coverage is already 100%, yet the description adds the decisive semantic the schema omits: the same string means different things depending on whether it contains a TLD. That directly changes how an agent should format the query.

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 outcome — availability and yearly price in ILS (VAT included) — plus the query expansion rule (bare label checks .co.il and .com, full name checks only that one). This clearly separates it from mutation siblings like buy_domain, though it never names an alternative explicitly.

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 pre-purchase lookup intent is implied by 'availability and yearly price', but there is no explicit when-to-use or when-not, and no pointer to domain_status, buy_domain, or attach_domain as the next step. An agent must infer the workflow position.

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