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

Annotations already cover the safety profile (readOnly, non-open-world, non-destructive), and the description adds real value on top: no live requests are made, unknown/excluded IDs and duplicates are surfaced explicitly, and results carry snapshot age, billing caveats, and affiliate disclosure. It stops short of describing ordering guarantees beyond 'caller order' or the result shape.

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 compare purpose and scope, and no sentence is obviously filler. The telegraphic, jargon-heavy phrasing ('compatible standard result-event rates', 'eligible success statistics') is dense but not padding.

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 single-param, read-only tool with no output schema and annotations covering safety, the description covers constraints, behavior (no live runs), input handling (duplicates/unknown IDs), and return caveats. Only the precise comparison output structure is left unstated.

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?

The sole parameter has zero schema description coverage, so the description must carry the meaning. It does so by specifying 'exact actor IDs', the 2-5 range matching min/maxItems, 'caller order', and that duplicates/unknown IDs are reported explicitly — genuinely adding semantics beyond the bare array schema.

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?

Names a specific verb+resource ('Compare ... exact actor IDs') and pins the scope to 'two to five'. It is distinguishable from same-family comparators (compare_scraping_apis, compare_proxy_providers) by resource, though it never explicitly contrasts itself with them.

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?

Usage is only implied: the metric restrictions ('saved usage, eligible success statistics...') and 'No actor runs or live requests' hint at when this is appropriate, but there is no explicit when-to-use, when-not, or named alternative such as find_scrapers or best_scraper.

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