Pwned Passwords (k-anonymity)

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

Goes well beyond the readOnly/openWorld/idempotent annotations by disclosing the privacy contract: local SHA-1 hashing, only the first 5 hex characters leaving the machine, and the guarantee that the password is never stored, logged, or echoed. That is exactly the behavioral context an agent needs before routing a secret into this 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?

Three tight sentences, no filler, with the operation front-loaded and the privacy mechanism immediately following. Every clause earns its place by adding either purpose or behavioral detail.

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, so the description ideally would say what comes back (pwned flag and breach count), and it is silent on the return shape and on any API-key/auth requirement. It compensates well on the input and privacy side, leaving only the response contract as a real gap.

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 0%, so the description must carry the load, and it does clarify the key semantic: either the plaintext password or its SHA-1 may be supplied, and the plaintext is hashed locally. It omits the 40-hex format constraint and the 1-256 length bounds, which the schema covers by pattern/maxLength.

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 if a password appears in known breaches') plus the mechanism (HIBP Pwned Passwords k-anonymity). This is unmistakably distinct from every sibling, which operate on emails, domains, CVEs, headers, or subdomains rather than credentials.

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?

Usage is only implied: an agent can infer this is the tool for credential-exposure checks, and the description contrasts with the email/domain breach siblings by operating on passwords. However, it never states when to prefer it (e.g., password audit vs. account breach lookup) or any exclusions, so it stays at minimum-viable guidance.

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