security_fetch_cve_epss

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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive. Description adds caching behavior (6-hour cache), source (FIRST.org), and return format (epss and percentile). Provides valuable context beyond annotations.

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?

Description is well-structured: purpose, parameter, return values, thresholds, usage note, source, example. Front-loaded with the key action. Each sentence is necessary and no redundant content.

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?

Tool is simple with one parameter and good annotations. Description covers all essential details: purpose, parameter format, return values, thresholds, caching, source, and guidance for integration with sibling tools. No gaps identified.

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 coverage is 100% for the single parameter cve_id. Description repeats the param definition and adds an example usage with the exact format, clarifying that quotes are needed. Baseline 3 plus example adds value.

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?

Description clearly states it returns the EPSS exploit probability score for a CVE, predicting exploitation likelihood in the next 30 days. It distinguishes from sibling tools like security_fetch_cve_detail by explaining EPSS measures urgency while CVSS measures severity.

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?

Provides explicit thresholds for action (patch immediately if >0.7, patch soon if 0.3-0.7, monitor if <0.3) and suggests using with security_fetch_cve_detail to prioritize patching. Does not explicitly state when not to use, but context is clear.

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