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

Annotations already declare the safety profile (readOnly, idempotent, non-destructive, openWorld). The description adds genuinely new behavioral context: the result is a 'rough' heuristic estimate derived from stated signals and is explicitly not a sales-based valuation, which sets the agent's expectation about output precision.

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 tight sentences, front-loaded with the core output, then the factors, then usage and exclusion. No 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?

For a read-only appraisal with no output schema, the description conveys that the return is a value range and lists the drivers. It stops short of saying how the range is expressed or whether confidence/caveats accompany it, a minor gap given the absence of an output schema.

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 0% and the single 'domain' parameter has no description, so the description carries the burden but only implies the input is a domain. It adds no format guidance (e.g., 'example.com' vs bare label) or edge-case handling, though the parameter is largely self-evident.

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 (appraise) and resource (a domain's value) and enumerates the exact factors used (length, pronounceability, TLD, age, same-name registrations). It also carves itself away from siblings by explicitly disclaiming a comparable-sales appraisal, which is what compare_prices/price_history 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?

Gives a concrete trigger (set a realistic budget before trying to buy a taken name) and an explicit exclusion (not a comparable-sales appraisal). An agent can route between this and the price_history/compare_prices siblings without opening schemas.

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