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

With annotations providing readOnlyHint=true, the description adds value by detailing exactly what the explanation covers (blind rail, three-share custody, commitments, revocation) and the optional topic focus. It does not contradict the read-only hint, and while it omits return format details, that is acceptable for a read-only explanatory 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?

The description is a single, information-dense sentence that front-loads the core purpose and includes substantive details (the trust rationale). Every clause adds value, with no filler or repetition.

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 tool with one optional parameter, full schema coverage, and no output schema, the description is complete. It explains the tool's purpose, the scope of the explanation, and the optional topic behavior, which is sufficient for correct use. Sibling context is not strictly necessary for an explanation tool.

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?

The schema covers the single parameter (topic) with an enum and description, plus the parent description adds 'Optionally focused on one topic' - somewhat redundant. With 100% schema coverage, baseline 3 is appropriate; the description does not add new parameter semantics beyond what the schema already provides.

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 opens with 'Plain-language explanation of what a KeyHalve verification verdict means', which uses a specific verb (explain) and resource (verdict). It clearly distinguishes from sibling tools keyhalve_status and keyhalve_verify by focusing on understanding rather than checking or verifying.

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 clear context: it is meant for explaining a verification verdict and why it can be trusted. It does not explicitly state alternatives or when not to use it, but the purpose is unambiguous enough that an agent would know when to invoke it. A minor gap is the lack of explicit 'use verify for actual verification' note.

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