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

Annotations already declare readOnlyHint=true and idempotentHint=true, which cover safety and idempotency. The description adds 'address check only' which clarifies the scope of the check, but it does not describe the return value or any network behavior. Since annotations carry the safety profile, a 3 is appropriate – the description adds some context but not rich behavioral detail.

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?

The description is a single, focused sentence that communicates the core function and a scope qualifier. There is no wasted wording, and the essential purpose is front-loaded before the 'address check only' clarifier.

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?

Given the simplicity of the tool (one parameter, annotations cover read-only and idempotency, no output schema), the description is mostly complete. Its only gap is not stating what the return value looks like (e.g., boolean), but this is a minor omission for a check-style tool where the result is intuitively a yes/no answer.

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 100% (the 'url' parameter has a clear description with an example). The tool description does not add any extra meaning about the parameter beyond what the schema already provides, so the baseline of 3 applies.

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 ('Check') and resource ('whether a web address is an official Ledger or Coinbase site'), and adds a clarifying scope ('address check only'). It is distinct from the sibling tools, which all deal with deals or guides, so there is no ambiguity about what this tool does.

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 description clearly implies when to use this tool (verifying a URL before trusting it), and the phrase 'address check only' signals that it does not perform deeper verification. However, it does not explicitly state when not to use it or name any alternative, though the siblings are unrelated, so confusion is minimal.

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