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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds that this queries a 'public' API and returns 'matching suffixes with prevalence counts,' which provides some behavioral context beyond the annotations (e.g., external dependency, response shape). However, it does not discuss rate limits, error behavior, or any side effects, so it contributes only modestly beyond structured metadata.

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, concise sentence that front-loads the core action and result. It contains no filler, redundancies, or extra clauses that dilute meaning. Every word contributes to understanding, and it is well-structured for quick parsing.

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 tool's moderate complexity (6 parameters, but only 1 required) and the presence of an output schema, the description is largely sufficient. It explains the core operation and the response format (suffixes + counts) without needing to detail every parameter, since those are schema-documented. Missing context like 'check if a password is compromised' would be nice, but the description achieves functional completeness.

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?

All six parameters have descriptions in the schema, giving 100% coverage. The description repeats the prefix concept (SHA-1/NTLM) but adds no new parameter-level semantics beyond the schema. With full schema coverage, the baseline score of 3 is appropriate; the description does not need to add much, and it does not.

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 ('Query'), a clear resource ('Pwned Passwords k-anonymity API'), and the exact operation (using a 5-character prefix, returning suffixes with prevalence counts). This clearly distinguishes it from sibling tools that deal with breach lists, stealer logs, and subscription data, leaving 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 provides no explicit guidance on when to use this tool versus alternatives, nor does it mention any conditions or exclusions. While the tool name and API reference imply it is for password-exposure checks, the description does not state this context or point to any sibling tools. An agent is left to infer the appropriate use case without explicit direction.

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