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

Annotations already declare readOnlyHint=true, openWorldHint=true and destructiveHint=false, so the safety and external-call profile is covered structurally. The description adds the meaningful semantic detail that the score is a 30-day forward-looking probability from FIRST.org, though it omits any note on return format (0-1 score plus percentile) or rate limits.

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?

One front-loaded sentence that identifies the source, the acronym, and the metric with no filler. It is tight but borderline terse, leaving no room for the usage caveats that would make it fully useful.

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?

For a one-parameter read-only lookup with a fully documented schema and no output schema, the description covers what the tool does but omits how the returned probability should be interpreted and how it relates to the other vulnerability tools in the set. Adequate but with visible gaps for an agent composing a vulnerability workflow.

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?

With a single required parameter at 100% schema description coverage, the schema already documents the 'cve' field and supplies format examples (CVE-2024-3094). The description adds nothing about the identifier format or validation, so the baseline of 3 applies.

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 names a specific verb and resource ('Query FIRST.org ... EPSS') and states the exact metric returned ('30-day real-world exploit probability'), so an agent knows what comes back. It does not, however, distinguish this from overlapping siblings such as cisa_kev_exploited_vulns or security_cve_audit.

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?

There is no explicit when-to-use guidance: nothing says to call this before or alongside cisa_kev_exploited_vulns or security_cve_audit, nor any condition under which it should be skipped. The agent must infer the routing decision from the tool name alone.

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