coso-mcp

An open Model Context Protocol server for internal-control reviews under the COSO Internal Control—Integrated Framework (ICIF-2013). It covers the full review lifecycle — scope → risk assessment → control register → population → sampling → testing → workpapers → review sign-off → deficiency evaluation → report — grounded in the framework's 5 components, 17 principles and points of focus.

• Local: runs over stdio (npx @simonmak-ascent/coso-mcp).
• Hosted: public endpoint at https://internal-control.ascent-partners.com/mcp (reference + read tools, plus an ephemeral per-session sandbox for the full write lifecycle — nothing persists).

Not audit or legal advice. This server assists with internal-control review methodology. All workpapers and assessments must be reviewed by qualified professionals before use in audit documentation.

Why this exists (competitive advantage)

Existing MCP servers either expose a vendor's GRC records (read-mostly, proprietary, product-shaped) or cover ISO 27001 / security controls. None runs a traceable COSO review. coso-mcp is the first COSO/ICFR-native, write-capable, open MCP for the whole lifecycle.

Dimension	coso-mcp	Vendor GRC MCPs (Workiva, Vanta, Drata, Optro, OpenPages, LogicGate…)	Community MCPs (iso27001-mcp, unidoc/isms, mcp-server-scf…)	AI skills (sox-testing / audit-support)
COSO ICIF-2013 native (5 components / 17 principles / points of focus)	✅ core engine	❌ product objects	❌ ISO/SCF-shaped	⚠️ text only
Full lifecycle to signed workpaper	✅	❌ retrieval; Workiva GRC tools are read-only	❌ planning/findings at best	⚠️ templates, not executable
Write/stateful workpapers + preparer/reviewer sign-off + audit trail	✅	❌ mostly read	❌	❌
Framework effectiveness (principle/component present & functioning)	✅	❌	❌	❌
Deterministic, reproducible computation (sample-size tables, seeded selection)	✅	partial	❌	❌ (freeform)
Open source + open access (MIT, public endpoint, no account)	✅	❌ paid platform	⚠️ some OSS	⚠️ not a server

Moat: it is the lifecycle layer, not the data layer — it can sit on top of Workiva/Vanta/Drata rather than compete for their data; its sampling and deficiency math are computed, not improvised; and openness gives zero-friction distribution no gated vendor can match.

Tools

Tool	Kind	Purpose
get_server_info	read	Server identity, framework coverage, disclaimer.
list_components	read	The five COSO components.
list_principles	read	The 17 principles (optionally filtered by component).
get_principle	read	A principle by number or slug, with paraphrased points of focus.
get_component	read	A component by id, with its principles.
list_objective_categories	read	Operations / reporting / compliance.
list_assertions	read	The CEAVOP assertions used to frame control objectives.
create_engagement	write	Create a review engagement.
get_engagement	read	Get an engagement by id.
list_engagements	read	List engagements.
add_scope_item	write	Add a significant account/process to scope.
list_scope_items	read	List scope items.
register_risk	write	Register a risk to objectives (likelihood, assertions, principles, fraud).
list_risks	read	List registered risks.
register_control	write	Register a control (type, frequency, linked risks, assertions).
list_controls	read	List registered controls.
get_audit_log	read	Append-only audit events for an engagement.
compute_sample_size	read	Recommended sample size from frequency × risk, with rationale.
create_population	write	Register a population (item list or declared size, bounded).
list_populations	read	List populations.
select_sample	write	Seeded, reproducible sample selection (random/systematic/targeted/haphazard).
record_test_result	write	Record attribute-level outcomes (pass/fail/na) and a conclusion.
list_test_results	read	List test results.
note_exception	write	Record an exception with root cause and impact.
list_exceptions	read	List exceptions.
assemble_workpaper	write	Assemble a Markdown control-testing workpaper.
list_workpapers	read	List workpapers.
get_workpaper	read	Get a workpaper with its Markdown.
add_review_note	write	Add a reviewer note.
resolve_review_note	write	Resolve a reviewer note.
sign_off	write	Preparer/reviewer sign-off (warns on same-person independence).
get_activity_log	read	Append-only activity log for an engagement.
classify_deficiency	write	Classify a deficiency (deficiency / significant / material weakness).
list_deficiencies	read	List deficiencies.
aggregate_deficiencies	read	Group and flag deficiencies that may aggregate.
assess_principle	read	Coverage indicators for one COSO principle.
assess_component	read	Coverage indicators for one COSO component.
framework_integration_check	read	Check all five components have coverage.
generate_report	read	Generate the Markdown review report.

Resources: coso://framework/icif-2013 (framework reference), coso://engagement/{id} (engagement bundle: scope, risks, controls). Prompts: scope-review, assess-risk, build-control-matrix, draft-test-workpaper, evaluate-deficiencies.

Usage

Local (stdio)

npx -y @simonmak-ascent/coso-mcp

Claude Desktop / generic MCP client config:

{
  "mcpServers": {
    "coso": {
      "command": "npx",
      "args": ["-y", "@simonmak-ascent/coso-mcp"]
    }
  }
}

Hosted (streamable HTTP)

https://internal-control.ascent-partners.com/mcp

The hosted endpoint is open. Write operations run in an ephemeral, isolated, rate-limited per-session sandbox and are not persisted.

Development

Compute runs on a box, never locally: cs run "<cmd>".

pnpm install
pnpm typecheck
pnpm test
pnpm test:coverage
pnpm build        # tsc

Security

See SECURITY.md. Report vulnerabilities privately — do not open a public issue.

Contributing

See CONTRIBUTING.md and the Code of Conduct.

License

MIT © Simon Mak / Ascent Partners Group Limited.