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

Annotations already declare readOnly/idempotent/non-destructive, but the description adds substantial context beyond them: a snapshot caveat that availability can change, the registrar/platform having final say, the fact it is not legal or trademark advice, the explanation that the score omits the trademark component, and a self-imposed daily call limit. This is exactly the extra behavioral disclosure that annotations cannot carry.

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?

Front-loaded with the trigger, then call mechanics, then limits and disclaimers — a logical order. It is dense but each sentence carries new information (platform list, score, caveats, exclusions); the only slight drag is the long parenthetical about the trademark gap.

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?

Return shape is covered by the output schema, and the description still explains the row count and what each row contains (check time, source, NameHound link). Constraints, disclaimers, rate limits and exclusions are all present, so nothing an agent needs to invoke or interpret the call 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 baseline is 3, but the description adds meaning the schema does not: 'Send one name per call' (clarifies no batching, in contrast to the strict string type) and the handle-derivation rule ('lowercase letters and numbers'). Only minor syntax detail is left, so it edges above baseline.

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 and resource ('check whether one specific name is free as a domain and as a handle') plus the exact platforms checked (.com/.net/.org/.app, Bluesky, Mastodon, GitLab, npm, PyPI) and the Brand Name Score output. An agent knows precisely what this tool returns without opening the schema.

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?

Opens with the trigger condition ('Use this when someone asks whether one specific... name is free') and closes with explicit exclusions: no brainstorming, no list-checking, no trademark clearance, no unsupported platforms. It even names the alternative path for the trademark gap (the user runs the free USPTO search).

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