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

Annotations already cover read-only and open-world behavior, while the description adds meaningful context: FIRST public API source, returned probability/percentile/date, predictive semantics, $0.002 USDC cost per successful x402 call, and that failed calls are not charged. This is strong disclosure beyond what the annotations provide.

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 front-loaded with what the tool returns, then the predictive caveat and alternative, then pricing and charge behavior. Each sentence carries useful information and there is no filler.

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 one parameter, a present output schema, and read-only/open-world annotations, the description covers purpose, semantics, alternative routing, payment requirements, and failed-call charging. Nothing critical for correct invocation 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?

There is only one parameter, and schema coverage is 100%: the schema fully documents cveId with an example. The description reinforces that the lookup is for one CVE, but adds no format or constraint beyond what the schema already says, so the baseline 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?

It states a specific resource and scope: the EPSS score for one CVE, including probability, percentile, and scoring date. It also distinguishes this predictive score from an exploit-existence check by pointing to cisa-known-exploits, so an agent can separate it from CVE-detail or KEV siblings.

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 EPSS predicts probability but does not say an exploit exists, and directs that case to cisa-known-exploits. That gives the agent both the implied use case and an explicit alternative/when-not condition.

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