key.verify (Rung 1, public)

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

It discloses key behavioral facts: it verifies signatures, can bind the record to a provided key, evaluates a liveness predicate with since, and holds no secret. However, it does not describe return values, failure modes, or side effects beyond verification.

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 dense but efficient, packing the action, formats, optional behaviors, and a safety note into a short space. The heavy use of domain jargon slightly reduces readability, but there is no obvious 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?

The description is sufficient for basic use and for optional since/key behavior, but it omits the meaning of horizonDays, does not state the output/return contract, and does not clarify how this tool relates to card_verify or compare_plain. Given the 4-parameter complexity, these are meaningful gaps.

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 description adds useful semantics for key binding and accepted vta formats, and explains since's role. However, horizonDays is left completely unexplained, and the key/vta formats remain jargon-heavy, leaving gaps in the parameter documentation.

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 identifies the action as verifying a signed VTA record, optionally checking key binding and evaluating liveness. It names the specific resource and scope, distinguishing it from sibling verification, derivation, and rendering tools.

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 conditional behavior for optional key and since parameters, but it does not explicitly state when to prefer key_verify over related tools such as card_verify, or when not to use it.

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