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

Beyond the readOnly/idempotent annotations it discloses ordering (most dangerous first), the searched name appearing first when listed, the 500 cap and that other API bases may differ, the meaning of total_hits and truncated (including null = unknown), and the false-negative caveat about buried hostnames. It also states the quota cost per call — strong disclosure for a mutation-free but quota-limited tool.

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-loads the core definition and keeps the caveats and cost in a compact single paragraph; nearly every sentence carries distinct information. It is dense and slightly run-on, but not padded.

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?

No output schema exists, and the description compensates by explaining the total_hits and truncated response fields, the ordering, and the quota cost, plus the known false-negative shape. An agent has everything needed to call and interpret the result 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 both parameters are already documented, and the schema itself explains that limit caps the API sample rather than the backend search. The description confirms 'at most 500' and per-host bound differences, adding only modest meaning on top of the 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?

States a specific verb and resource (find lookalike domains) and enumerates the exact categories: typosquats, homoglyphs, other TLDs/hosting platforms, phishing-word wrapping. The examples ("paypal" read as paypal.com, login.paypal.com) let an agent distinguish it from sibling check_indicator without opening a 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?

Explicitly routes follow-up work to check_indicator / check_indicators for verdicts, making the search-vs-verdict split clear. It also warns that an empty result does not prove absence, which prevents misuse. It stops short of naming when to prefer check_url or scan_before_use, so not a full when/when-not matrix.

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