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

With no annotations provided, the description carries the full burden. It discloses return behavior (number of breaches and involved services) and privacy handling (address partially masked). This is meaningful behavioral context, though it does not cover all aspects like rate limits or error states.

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 three sentences long, front-loads the core action, and every sentence earns its place: what it does, what it returns, positioning, and privacy note. No redundancy or fluff.

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 simple single-parameter lookup tool, the description covers the key aspects: purpose, return values, data source, and masking. It doesn't enumerate failure modes or response structures, but given no output schema and low complexity, it is adequately complete, just missing a few edge-case details.

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% for the single 'email' parameter, including an example. The description adds no extra parameter details, so the baseline of 3 applies. It doesn't compensate further but doesn't need to given the schema is adequate.

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 the tool's function: 'Check whether an email address appears in known data breaches, using the XposedOrNot breach database.' This provides a specific verb, resource, and context, and it distinguishes the tool from siblings like email_auth_check by focusing on breach data.

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 gives clear context for use—checking an email against known breaches—and positions it as a 'free alternative to paid breach-lookup APIs.' However, it does not explicitly state when not to use it or contrast it with sibling tools (e.g., email_auth_check), so it lacks explicit alternatives or exclusions.

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