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

Adds substantial context beyond the readOnly/openWorld annotations: the k-anonymity mechanism (only the first 5 hash characters reach Have I Been Pwned), the 50-hash batch ceiling, and the $0.002 USDC x402 cost per call. These are exactly the traits an agent needs before invoking a paid, privacy-sensitive service.

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?

Four short sentences, front-loaded with what the tool does, then the input constraint, then the batch limit and cost. Each sentence carries distinct, necessary information with no filler.

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-parameter read-only tool with no output schema, the description covers purpose, input semantics, privacy mechanics, batch limits and pricing. Nothing an agent needs in order to call it correctly is absent.

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% and documents the comma-separated 40-hex format, so baseline is 3. The description goes further by clarifying that the value must be a hash rather than the password itself and explaining what portion of it is transmitted externally, adding real meaning about what to pass.

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 ('Breached password check') and states the exact question answered — whether a password appears in known breaches and how often. No sibling overlaps with this capability, so an agent can immediately tell what it 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?

Gives concrete operational guidance: send only the SHA-1 hash, never the raw password, and up to 50 hashes per call. It does not name when-not-to-use or an alternative tool, but no sibling competes for this task, so the missing exclusion is minor.

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