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

Annotations already declare readOnly, openWorld, idempotent, and non-destructive behavior. The description adds meaningful behavioral detail: the 36,000-block expiry rule, the distinction between estimated and real expiry dates, and the renewal mechanism. This goes well beyond the annotation surface.

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?

The description is compact and front-loaded, with the core capability ('Check up to 25 names at once') stated first. The second sentence earns its place by explaining the expiry mechanism necessary for interpreting the results. No filler or redundant wording.

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?

Given the presence of an output schema and strongly informative annotations, the description covers what the tool does, its batch limit, its status vocabulary, and the underlying expiry rule. Nothing essential for selecting or invoking this tool 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 coverage is 100%, so the schema already explains both names and warn_days. The description adds context about the statuses and expiry calculation, but it does not materially enhance parameter-level understanding beyond what the schema supplies. A 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 ('Check') and resource ('names expiry'), and enumerates concrete outputs (status, blocks left, estimated/real expiry dates). It distinguishes itself from siblings by emphasizing the batch capability of up to 25 names at once, which lookup_name and search_names do not offer.

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 clearly indicates this is for checking multiple names in one call and provides the expiry rule context. It does not explicitly name alternatives or say when not to use it, but the batch-oriented wording and sibling names make the intended use clear.

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