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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, lowering the bar. The description adds real behavioral context beyond them: the two-feed composition, verbatim inclusion of CISA's required-action text, and the conditional support-status join when a version is passed. No contradiction with annotations; only data freshness is left unstated.

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?

Two sentences, front-loaded with the core purpose ('The exploited-vulnerability record for a product') before the detail. The parentheticals are dense but each earns its place — EOL relevance and the unpatchable definition — though the single long sentence is somewhat hard to scan.

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?

With an output schema present and safety annotations supplied, the description needn't explain return values or read-only behavior. It covers data provenance, the optional version join, and the EOL nuance; only minor items like data freshness or empty-feed behavior are absent.

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 both parameters are already documented. The description's 'Pass an optional version to include its support status alongside' largely restates the schema's 'Optional version/cycle to check support status for,' adding no new parameter-level meaning.

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?

States a specific resource — the exploited-vulnerability record for a product from CISA's KEV catalog plus endoflife.ai's Exploited & Unpatchable feed — and enumerates the fields returned (CVEs, date added, federal due date, verbatim action text). This content-level specificity cleanly separates it from siblings like check_eol and get_risk_score without naming them.

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?

Gives clear context on when the data matters — the 'discontinue use' entries are flagged as the ones that matter for end-of-life versions — and explains the optional version parameter's effect ('include its support status alongside'). It stops short of a 5 because it never explicitly names alternatives or states when-not-to-use.

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