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

With no annotations, the description carries full burden. It discloses key behaviors: SHA-1 prefix, k-anonymity, no plaintext sent, payment mechanism, and return of 402 accept-list without payment. It does not detail the response format when payment is provided, but the core behavioral traits are adequately transparent.

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 sentences, front-loaded with the primary purpose. Each sentence adds essential information without redundancy or fluff. Efficient and well-structured.

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 is provided, so the description should indicate the return format. It mentions the 402 accept-list for unpaid requests, but does not specify what the paid response looks like (e.g., boolean, count, or match data). This is a noticeable gap, though the tool is simple and the main behavior is covered.

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%, and the description adds meaningful context beyond the schema: it explains that _payment is for signed authorization and what happens if absent, and it clarifies the sha1_prefix purpose in privacy terms. This adds value over the schema alone.

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?

Describes a specific verb and resource: 'Check whether a password hash prefix (SHA-1, first 5 chars) appears in the HIBP breach corpus.' The purpose is unambiguous and distinct from sibling tools, which are unrelated (e.g., audit_comp_live_listings, check_drift_exposure).

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?

Explains the privacy property (k-anonymity, no plaintext sent), pricing, and the two modes of operation (with or without _payment). Provides clear context on how to use the payment parameter, though it does not explicitly exclude alternative tools or scenarios.

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