breachList

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

Annotations already declare readOnlyHint=true, openWorldHint=true and destructiveHint=false, so the safety profile is covered. The description adds genuinely new operational context beyond the structured data: the endpoint is free and requires no API key, which affects how an agent should call it. It omits return volume/paging behavior, keeping it from a 5.

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 short sentences, no filler, with the core action front-loaded and the auth detail trailing as supporting context. Every sentence carries distinct information.

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 zero-required-param read-only list tool with a fully documented schema and no output schema, the description covers what it does, the optional filter, and the auth model. The only gap is any note on result size or ordering, which is minor here.

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?

With 100% schema description coverage, the schema already documents the single 'domain' parameter and even gives an example ('adobe.com'). The description only restates that filtering by domain is optional, adding no syntax or format detail beyond the schema, 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 gives a specific verb (list) plus resource (data breaches) and names the source (HaveIBeenPwned), which is enough for an agent to know what it returns. It does not explicitly distinguish itself from close siblings like breachLatest, breachGet, or breachSearch, though 'all known' implicitly contrasts with a 'latest' variant.

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: 'Optionally filter by domain' hints at a browsing/listing use case, but nothing states when to prefer this over breachGet (single breach details) or breachSearch (account lookup). No when-not guidance is offered.

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