ZEN SecDB

kev_check

Read-onlyIdempotent

Check whether one or more CVEs are listed in the CISA KEV or EU KEV catalogs of known exploited vulnerabilities.

What this tool does

For each CVE, returns whether it is in a KEV catalog and, if so, the dates, the known use in ransomware campaigns, and the threat actors reported by the EU catalog.

When to use this tool

Use this tool when the user asks:

"Is this CVE in CISA KEV?"
"Which of these CVEs are known to be exploited?"
to prioritize a list of CVEs

For a single CVE, this is lighter than vulnerability_info. To find the entries of a catalog by date, vendor, or product, use kev_list.

Inputs

cve_ids: list of CVE identifiers (CVE-YYYY-NNNNN), up to 100.

Outputs

results: one object for each CVE, containing:
- cve_id
- in_kev: whether the CVE is in at least one KEV catalog
- when in_kev is true: in_cisa, in_eu, vendor, product, vulnerability_name, ransomware, cisa_added_date, cisa_due_date, eu_reported_date, euvd_id, eu_exploitation_type, eu_threat_actors_exploiting

LLM usage guidelines

Send all the CVEs in one call instead of calling the tool once per CVE.
in_kev: false means that the CVE is not in these catalogs, not that it is not exploited: use sightings_search for other evidence.
in_kev: false does not confirm that the CVE exists: use vulnerability_score or vulnerability_info to check it.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "cve_ids": "<cve_ids>"
    },
    "name": "kev_check"
  }
}

Input Schema

Name	Required	Description	Default
`cve_ids`	Yes	CVE identifiers (CVE-YYYY-NNNNN)

Output Schema

Name	Required	Description	Default
`results`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

AddedNov 3, 2026

TDQS

A4.6/5.0

Behavior4/5

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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety profile is covered. The description still adds real behavioral value by defining what `in_kev: false` does and does not mean — a classic misreading trap — and by stating that all CVEs should be sent in a single call. It does not discuss latency or failure behavior for invalid IDs, but the core semantics are disclosed.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded purpose sentence, then clearly separated sections for inputs, outputs, and usage rules — easy to skim. The enumerated output field list is largely redundant with the existing output schema and is the one block that does not fully earn its space.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

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, an agent has everything needed: valid input format, batch size, return shape, sibling alternatives, and interpretive caveats for the negative case. Nothing required to call it correctly is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% with a single required parameter, so the baseline is 3. The description goes beyond the schema by stating the batching intent (send all CVEs in one call rather than looping) and pairing the format with the catalog rationale, giving the 100-item limit practical meaning rather than just a constraint.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource (check CVEs against CISA KEV and EU KEV catalogs) and immediately scopes what is returned per CVE. It explicitly differentiates itself from `kev_list` (catalog browsing) and `vulnerability_info` (single-CVE detail), so an agent can route correctly without reading schemas.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Provides concrete trigger phrases ("Is this CVE in CISA KEV?", prioritizing a CVE list), names the alternative for the catalog-browsing case, and adds negative guidance in the usage rules (use `sightings_search` for other exploitation evidence, `vulnerability_score`/`vulnerability_info` to confirm existence). When-to-use, when-not-to-use, and alternatives are all present.

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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