cisa-cybersecurity-mcp-server

cisa_list_reference

cisa_list_reference

Read-onlyIdempotent

Decode the vocabulary the other CISA tools take as input. Topics cover the BOD 26-04 remediation timeline table and what each tier means, the KEV record fields and their value domains, the SSVC decision points CISA publishes, the critical-infrastructure sector names as the advisory corpus spells them, advisory ID formats, CVSS severity bands, and the freshness of the data this server currently holds. Call this before constructing filters for cisa_search_kev or cisa_search_ics_advisories, and whenever another tool's recovery hint points here.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`topic`	Yes	Which reference block to return: directives (BOD 26-04 Table 1 and its definitions), kev_fields, ssvc_values, sectors, advisory_id_formats, severity_bands, or sources (what this server currently holds).

Output Schema

TableJSON Schema

Name	Required	Description
`error`	No	Present when the call failed. Absent on success.
`title`	No	Human-readable title for the topic.
`topic`	No	The topic that was decoded.
`entries`	No	The decoded terms for this topic.
`sources`	No	Topic sources only — what this server currently holds, read from in-process state.
`summary`	No	What this topic covers and when to reach for it.
`supersedes`	No	Topic directives only — the directives BOD 26-04 supersedes and revokes.
`definitions`	No	Topic directives only — supporting definitions from the directive text.
`timelineTable`	No	Topic directives only — all sixteen rows of BOD 26-04 Appendix A, Table 1.

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedSep 25, 2026

addedOutput schema / properties / sources / properties / csafMirror / properties / unavailableReason

Added value: +{
+  "description": "Present only when the index cannot be opened: its location is not writable, is read-only, has a missing directory, runs through a file, or holds a file that is not a SQLite database. Fixed by CISA_CSAF_MIRROR_PATH, not by waiting.",
+  "enum": [
+    "not_writable",
+    "read_only",
+    "missing_directory",
+    "not_a_directory",
+    "not_a_database"
+  ],
+  "type": "string"
+}

changedOutput schema / properties / sources / properties / kev / properties / refreshCron / description

Previous value: -"Cron expression the refresh poll runs on."New value: +"Cron expression the refresh poll runs on, or off when it is disabled."

First observedSep 20, 2026

TDQS

A4.5/5.0

Behavior4/5

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

Annotations already declare readOnlyHint=true and idempotentHint=true, so the safety profile is covered. The description adds useful context beyond the annotations: the tool returns server-held reference data, tracks freshness, and one topic reports 'what this server currently holds.'

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

Conciseness5/5

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

The description is two sentences: the first front-loads the purpose, and the second packs the topic list and usage triggers into one scannable sentence. Every clause earns its place; there is no filler.

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 single-parameter, read-only lookup with an output schema, the description is fully sufficient. It states what the tool returns, which reference blocks are available, and exactly when to call it, so no operational gaps remain.

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

Parameters3/5

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

Schema description coverage is 100% and the single topic parameter has a fully explained enum. The description echoes those enum values but does not add meaning beyond the schema, so the baseline of 3 is appropriate.

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?

The description uses a specific verb ('Decode') and names the resource ('the vocabulary the other CISA tools take as input'), then enumerates the concrete topic domains it covers. This clearly distinguishes it from the sibling search/get tools.

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?

It explicitly instructs the agent to call this tool before constructing filters for cisa_search_kev or cisa_search_ics_advisories, and whenever another tool's recovery hint points here. This is direct, actionable when-to-use guidance with named alternatives.

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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