Get the EPSS exploit-probability score (0-1) and percentile for one or more CVEs — the likelihood each is exploited in the next 30 days. Use it to prioritize patching. Pass cve_id for one, or cve_ids (array or comma-separated) for many. Source: FIRST.org EPSS.
| Name | Required | Description | Default |
|---|---|---|---|
| cve_id | No | A single CVE id. | |
| cve_ids | No | Multiple CVE ids (or pass a comma-separated string). |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are present, so the description carries the full burden. It discloses the output (score 0-1, percentile), the time horizon, the source (FIRST.org EPSS), and the input multiplicity. It does not cover rate limits or error behavior, but for a simple read-style API the provided behavioral context is solid.
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?
Three concise sentences, each earning its place: what it returns, when to use it, and how to pass parameters. The source attribution is a useful addition without bloating the text.
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 no output schema, the description appropriately explains both the return values and the decision context. It leaves out exact response formatting for multiple CVEs and the percentile scale, but it supplies enough for an agent to invoke it correctly and interpret the high-level result.
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%, so the baseline is 3. The description adds helpful instructions by mapping cve_id to single CVE use and cve_ids to many, including the array or comma-separated variant. It could be slightly clearer that at least one of the two parameters should be supplied, but the intended usage is clear.
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: get the EPSS exploit-probability score and percentile for one or more CVEs. It also explains the 30-day likelihood meaning, which clearly distinguishes this from generic CVE lookup 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?
It explicitly says 'Use it to prioritize patching,' giving a clear decision context. It does not explicitly contrast with sibling tools like cve_lookup or known_exploited, but the purpose is specific enough that an agent can infer when this tool is appropriate.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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