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

Beyond the annotations (readOnly, idempotent, non-destructive) it discloses several operationally important traits: no API key required, rate-limited, and that the phishing check of a front page 'may render it' - a real side effect an agent should know about. The remaining gap is that it does not say how rate limits manifest (error vs. throttle) or how long a check takes, but the added context is substantive.

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?

One front-loaded sentence that leads with the core question, then parenthetically expands scope and verdict meanings - efficient for the amount of decision-relevant information packed in. The exchange-name parenthetical list is slightly baggy but is genuinely useful for matching, so the length is largely earned.

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?

Even though an output schema exists, the description pre-explains the four verdicts precisely (including the subtle official/danger/not_official distinction, where a name alone is not impersonation), which is the exact ambiguity an agent would otherwise mis-handle. With the side-effect disclosure and source-of-truth description, an agent has everything needed to call it and interpret results 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% with a single required 'domain' parameter, so the schema already carries the baseline. The description still adds value by clarifying that a link/URL is also acceptable input and by explaining what happens for a domain that embeds an exchange name (registration date, first certificate, phishing check).

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 a domain or link is the official address of a crypto exchange, wallet or dApp') and enumerates the coverage (Korean exchanges, global exchanges, wallets, dApps). It clearly distinguishes itself from neighbors like phishing_link_check and wallet_address_check by naming the exact verdict vocabulary and the reference sources it compares against.

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 enumerated domain types (exchange / wallet / dApp) and the four verdicts give strong implied guidance about when this tool is the right one, and the 'compared with the addresses the companies publish themselves' clause explains how the judgment is made. It stops short of explicitly naming an alternative (e.g., phishing_link_check for non-exchange links) or a when-not-to-use condition, so it does not reach 5.

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