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

The annotations already declare readOnlyHint=true and destructiveHint=false, so the core safety profile is covered. The description adds valuable behavioral context beyond annotations: it is 'Free' (no cost), 'no-lookup' (does not perform an actual lookup), and imposes a strict privacy constraint ('Never include an email address or other owner identifier'). No contradiction with annotations; this extra context earns a 4.

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, information-dense sentence followed by one imperative constraint. It front-loads the core purpose ('Free, no-lookup decision aid'), then immediately lists triggers and the key privacy rule. Every word earns its place, with no fluff or redundancy.

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 simplicity (one parameter, full schema, complete annotations, output schema present), the description is fully complete. It covers purpose, usage triggers, input constraints, and behavioral traits. There is no missing critical context for an agent to select and invoke this tool correctly.

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%, so the parameter is already well-documented. The description adds semantic value by listing concrete scenario examples (suspicious login, credential exposure, sensitive-service connection) that clarify what kind of input is expected. This goes beyond the schema's generic 'non-identifying description', so a 4 is appropriate.

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 clearly states a specific verb ('decide whether to recommend') and resource ('an owner-approved Breach402 check'), while also listing the exact trigger scenarios (suspicious login, credential exposure, phishing, etc.). It distinguishes itself from sibling tools by explicitly labeling itself as a 'Free, no-lookup decision aid', which contrasts with the lookup and execution tools like get_breach_report and prepare_paid_breach_check.

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 explicit when-to-use guidance by enumerating the security concerns that warrant this tool (suspicious login, phishing, monthly-review, etc.). It also implies when-not-to-use via 'no-lookup' (i.e., for actual data retrieval, use a lookup tool). However, it does not explicitly name alternative tools, so it stops short of a 5.

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