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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so safety is covered. The description adds value beyond that: it discloses that methods defaults to screenshot, that results are paginated, and exactly what fields each result carries (URL, final URL, title, match reason). It could still say more about rate limits or result caps, but this is solid added context.

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?

A dense but single-purpose paragraph, front-loaded with what the tool does and the matching methods before the use case. Every clause earns its place, though the run-on list of return fields makes it slightly heavy.

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?

With an output schema present the description needn't explain returns (it does anyway), and annotations cover the safety profile. It supplies the matching semantics, the default method, pagination, and scan_id meaning, so an agent has enough to call it 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 description coverage is 0%, so the description carries the param burden. It clarifies scan_id ("the UUID of a ScanMalware scan") and explains methods (default screenshot), but page and limit are only implied by the word "paginated" with no format or bounds. Partial compensation for a complete coverage gap.

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 ("Find scans") and resource, and enumerates the matching methods (screenshot similarity, favicon, fuzzy page hash) with the default. It adds context beyond the name by noting the default method is screenshot, but it never names the closely-related siblings (search_similar_screenshots, search_by_screenshot_hash, search_by_favicon) to distinguish this composite search from those single-method tools.

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 line "Useful for finding copies of a phishing page on other hosts" gives a concrete use case, which is more than nothing. However, it offers no guidance on when to pick this multi-method search over the single-method siblings, nor any exclusions or prerequisites.

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