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.