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

Annotations already indicate read-only, idempotent, and non-destructive behavior. The description adds valuable context beyond that: it explains that on failure it 'tries the specific wrong constructions developers actually write' and provides privacy assurances about the signing secret ('never stored, logged or counted'). This goes beyond the basic annotation hints.

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 concise and well-structured. It opens with the core action, then explains diagnostic behavior, usage context, and a privacy note. Every sentence adds useful information without 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?

Given the tool's simplicity (3 required params, no output schema) and strong annotations, the description is complete. It covers what, when, and important security context. The output behavior is implied by 'tells you which mistake you made,' so no critical information is missing.

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%, so the baseline is 3. The description reinforces the parameter semantics by explaining the purpose of the signing secret and its handling, but does not add significant new meaning beyond the schema's already detailed field descriptions.

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 exactly what the tool does: 'Check a ROKI-Signature header against the raw body and the signing secret.' It also distinguishes itself from sibling tools by focusing on webhook signature verification and diagnostic failure analysis, making the purpose clear and unique.

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 explicitly says 'Use it whenever webhook verification rejects real events,' providing clear when-to-use guidance. It doesn't explicitly mention alternatives or when not to use it, but the context is strong enough for an agent to select it appropriately.

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