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

With annotations already covering safety (readOnlyHint=false, destructiveHint=false), the description adds rich behavioral context: it uses saved/cached evidence, makes no new availability requests, treats cache misses as 'Not confirmed', and returns standard offers, premium facts, dates and links. It does not detail idempotency or openWorldHint, but those are already annotated.

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?

Dense but tightly packed with useful constraints, front-loaded with sequencing and scope. Some sentences pack multiple ideas ('Returns standard reference offers, premium facts, dates and links.'), but nothing is wasted.

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 comparison tool with no output schema and 100% schema coverage, the description covers prerequisites, pricing basis, cache behavior, return shape, and result-size limits. It leaves minor unknowns (exact ordering of comparison) but is otherwise sufficient to call 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?

Schema coverage is 100%, so the baseline is 3. The description reinforces the 10-domain cap and price orientation but adds no syntax or format details beyond the schema's own description of comma/whitespace separation and renewal cents.

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 and resource ('compare up to 10 candidates') and explicitly distinguishes itself from siblings ('After checking exact names with the availability tools', 'Does not generate names', 'No new availability requests'). An agent can tell it apart from check_availability and get_naming_guidance without opening schemas.

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?

It gives explicit sequencing ('After checking exact names'), bounded scope ('up to 10 candidates', 'Split larger lists into bounded groups'), and what not to expect ('Does not generate names'). This is near-complete routing and boundary guidance.

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