MCP Server for OSCAL

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MCP Server for OSCAL

Instant OSCAL expertise for your favorite AI agent

A Model Context Protocol (MCP) server that provides AI assistants (Claude, Cline, Kiro, Claude Code, etc.) with tools to work with NIST's Open Security Controls Assessment Language (OSCAL). Like many early adopters, we needed help implementing OSCAL proofs-of-concept to demonstrate value to business stakeholders. Perhaps due to limited availability of examples in the public domain, we found that most AI agents/LLMs alone produced inconsistent results related to OSCAL. The tools in this MCP server minimized that problem for our use-case and we hope it does the same for you.

[!TIP]

To get started, see Installation below.

Contents

• Features: what the tools cover, local-only operation, and integrity checks
• What is OSCAL? and What is MCP?: background
• How to use / examples: sample sessions covering models, templates, catalogs, and AWS component definitions
• Installation: one-click MCP Bundle (.mcpb) for Claude Desktop, or the PyPI package with configuration for Kiro, Claude Desktop, and VS Code
• Using your own OSCAL Content: OSCAL_DOCUMENTS_DIR and store settings
• OSCAL Agent: the standalone Strands/Bedrock agent, sessions, and conversation management
• Development, Security, Known limitations, Related projects, License

Features

Together, the tools provided by this MCP server are meant to enable your preferred AI assistant to provide accurate, authoritative guidance about OSCAL architecture, models, use-cases, requirements, and implementation. You don't need to understand the tools to use them, but details are in the tools directory.

The server is lightweight and meant to run locally without additional setup. By default, it uses stdio protocol for MCP transport. Do not attempt to use the server with streamable-http transport, as we've not yet implemented transport security or authentication.

The default tools should not connect to any remote services or resources - all required content is bundled with the server. As a security measure, we've implemented basic file integrity verification for bundled content. At build-time we generate manifests including SHA-256 hashes of the bundled OSCAL schemas and the pre-built content database. Each time the server starts, both are verified against their manifests. A schema mismatch produces an error and prevents startup; a database mismatch causes the server to discard the bundled database and start with an empty one.

The tools cover OSCAL schemas and model metadata, Metaschema allowed-values, constraint, reference, and definition lookup plus source reading (get_allowed_values, get_constraints, find_references_to, get_definition, get_metaschema_source), multi-level content validation, Component Definition navigation, query/list/full-text search for every OSCAL model type (catalogs, profiles, SSPs, assessment plans and results, POA&Ms, mapping collections), community resources, and documentation. Search tools come in search/fetch pairs: text_search_oscal returns element IDs plus parentDocumentUuid that get_child_element resolves, and query_oscal_documentation returns paged {title, snippet} passages, with a docId on local pages that get_oscal_documentation reads as a line range. Results never include filesystem paths. See the tools README for the full list.

In addition to the MCP server, the package includes a standalone OSCAL agent built with Strands Agents. See the OSCAL Agent section below.

What is OSCAL?

OSCAL (Open Security Controls Assessment Language) is a set of framework-agnostic, vendor-neutral, machine-readable schemas developed by NIST that describe the full life cycle of GRC (governance, risk, compliance) artifacts, from controls to remediation plans. OSCAL enables automation of GRC workflows by replacing digital paper (spreadsheets, PDFs, etc.) with a standard-based structured data format. To learn more about OSCAL, install this MCP server then ask your AI. Or see the official OSCAL website.

What is MCP?

MCP (Model Context Protocol) is an open-source standard for connecting AI applications to external systems. Think of MCP like a USB-C port for AI applications. Just as USB-C provides a standardized way to connect electronic devices, MCP provides a standardized way to connect AI applications to external systems.

How to use / examples

Examples below were created with kiro-cli, but should work with any AI assistant that supports MCP servers.

Example 1: Learn about available OSCAL models

 % kiro-cli

/tools trust get_oscal_schema list_oscal_models list_oscal_resources

Tools '@oscal/get_oscal_schema', '@oscal/list_oscal_models', '@oscal/list_oscal_resources' are now trusted. I will not ask for confirmation before running these tools.

How many GA OSCAL models are there?

I'll check the available OSCAL models to find out how many are in GA (Generally Available) status.

Running tool list_oscal_models with the param (from mcp server: oscal) ⋮ {}

• Completed in 0.1s

There are 8 GA OSCAL models:

Control Layer (3):

• Catalog
• Profile
• Mapping Collection

Implementation Layer (2):

• Component Definition
• System Security Plan (SSP)

Assessment Layer (3):

• Assessment Plan (SAP)
• Assessment Results (SAR)
• Plan of Action and Milestones (POA&M)

All of these models have "GA" (Generally Available) status, meaning they are stable and ready for production use. ▸ Time: 8s

Example 2: OSCAL template generation

> generate a minimum, valid, OSCAL mapping in JSON for use as a template.

I'll help you create a minimal, valid OSCAL mapping in JSON. Let me first check what OSCAL models are available to understand the structure.

Running tool list_oscal_models with the param (from mcp server: oscal) ⋮ {}

• Completed in 0.1s

Now let me get the schema for the mapping-collection model to understand its structure:

Running tool get_oscal_schema with the param (from mcp server: oscal) ⋮ { ⋮ "model_name": "mapping-collection", ⋮ "schema_type": "json" ⋮ }

• Completed in 0.14s

Based on the schema, I'll create a minimal, valid OSCAL mapping collection template. Here's the absolute minimum required structure:

I'll create the following file: ./oscal-mapping-template.json (using tool: write) Purpose: Create minimal OSCAL mapping collection template

• 1: {
• 2: "mapping-collection": {
• 3: "uuid": "12345678-1234-4567-8901-123456789012",
• 4: "metadata": {
• 5: "title": "Sample Mapping Collection",
• 6: "last-modified": "2026-01-06T20:46:28.034Z",
• 7: "version": "1.0",
• 8: "oscal-version": "1.2.0"
• 9: },
• 10: "provenance": {
• 11: "method": "human",
• 12: "matching-rationale": "semantic",
• 13: "status": "draft",
• 14: "mapping-description": "Sample mapping between two control frameworks"
• 15: },
• 16: "mappings": [
• 17: {
• 18: "uuid": "87654321-4321-7654-1098-210987654321",
• 19: "source-resource": {
• 20: "type": "catalog",
• 21: "href": "https://example.com/source-catalog.json"
• 22: },
• 23: "target-resource": {
• 24: "type": "catalog",
• 25: "href": "https://example.com/target-catalog.json"
• 26: },
• 27: "maps": [
• 28: {
• 29: "uuid": "11111111-2222-3333-4444-555555555555",
• 30: "relationship": "equivalent",
• 31: "sources": [
• 32: {
• 33: "type": "control",
• 34: "id-ref": "ac-1"
• 35: }
• 36: ],
• 37: "targets": [
• 38: {
• 39: "type": "control",
• 40: "id-ref": "access-control-policy"
• 41: }
• 42: ]
• 43: }
• 44: ]
• 45: }
• 46: ]
• 47: }
• 48: }

Creating: ./oscal-mapping-template.json

• Completed in 0.8s

I've created a minimal, valid OSCAL mapping collection template at ./oscal-mapping-template.json. This template includes:

Required elements:

• uuid: Unique identifier for the mapping collection
• metadata: Document metadata with title, last-modified timestamp, version, and OSCAL version
• provenance: Mapping methodology information including method, matching rationale, status, and description
• mappings: Array containing at least one mapping with:
• uuid: Mapping identifier
• source-resource and target-resource: References to the catalogs being mapped
• maps: Array with mapping entries showing relationships between controls

Key features:

• Uses placeholder UUIDs (replace with actual UUIDs in production)
• Maps a source control "ac-1" to target control "access-control-policy" with "equivalent" relationship
• Includes minimal required fields only
• Valid JSON structure conforming to OSCAL 1.2.0 schema

You can customize this template by:

• Replacing placeholder UUIDs with real ones
• Updating the resource URLs to point to actual catalogs
• Adding more mapping entries in the maps array
• Modifying control IDs and relationships as needed

▸ Time: 21s

Example 3: Discover open source OSCAL catalogs

> What are some open source OSCAL catalogs?

Running tool list_oscal_resources with the param (from mcp server: oscal) ⋮ {}

• Completed in 0.51s

Based on the OSCAL community resources, here are some notable open source OSCAL catalogs:

Government/Official Catalogs

Australian Cyber Security Centre (ACSC)

• Information Security Manual (ISM) controls in OSCAL format
• Essential Eight Maturity Levels (ML1, ML2, ML3)
• Available at: https://www.cyber.gov.au/ism/oscal

CMS Acceptable Risk Safeguards (ARS)

• Tailored NIST SP 800-53 controls for Centers for Medicare and Medicaid Services
• Available at: https://github.com/CMSgov/ars-machine-readable

GovTech Singapore

• ICT&SS Policy catalog and profile for low-risk systems
• Available at: https://github.com/GovtechSG/tech-standards

Industry/Standards Organizations

Center for Inter