OpenCap Stack MCP Server

The @opencapstack/mcp-server gives any MCP-compatible AI agent direct access to your cap table — no REST calls, no boilerplate. Ask Claude to "show me the cap table" or "issue 50,000 options to Jane Doe" and it happens.

npm install -g @opencapstack/mcp-server

29 tools covering stakeholders, equity, SAFEs, valuations, documents, and analytics.

Setup

Claude Code

Add to ~/.claude.json (global) or .claude/settings.json (project):

{
  "mcpServers": {
    "opencap": {
      "command": "npx",
      "args": ["-y", "@opencapstack/mcp-server"],
      "env": {
        "OPENCAP_API_KEY": "your-api-key",
        "OPENCAP_BASE_URL": "https://api.opencapstack.com/api/v1"
      }
    }
  }
}

Base URL

Include /api/v1 in OPENCAP_BASE_URL. Without it all requests will 404.

Cursor

Add to .cursor/mcp.json in your project root:

{
  "mcpServers": {
    "opencap": {
      "command": "npx",
      "args": ["-y", "@opencapstack/mcp-server"],
      "env": {
        "OPENCAP_API_KEY": "your-api-key",
        "OPENCAP_BASE_URL": "https://api.opencapstack.com/api/v1"
      }
    }
  }
}

Windsurf

Add to ~/.codeium/windsurf/mcp_config.json:

{
  "mcpServers": {
    "opencap": {
      "command": "npx",
      "args": ["-y", "@opencapstack/mcp-server"],
      "env": {
        "OPENCAP_API_KEY": "your-api-key",
        "OPENCAP_BASE_URL": "https://api.opencapstack.com/api/v1"
      }
    }
  }
}

Claude Desktop

Add to ~/Library/Application Support/Claude/claude_desktop_config.json (macOS):

{
  "mcpServers": {
    "opencap": {
      "command": "npx",
      "args": ["-y", "@opencapstack/mcp-server"],
      "env": {
        "OPENCAP_API_KEY": "your-api-key",
        "OPENCAP_BASE_URL": "https://api.opencapstack.com/api/v1"
      }
    }
  }
}

Getting Your API Key

Option A — Agent onboarding (zero human steps):

curl -X POST https://api.opencapstack.com/api/v1/agents/onboard \
  -H "Content-Type: application/json" \
  -d '{
    "agent_id": "claude-mcp",
    "agent_name": "Claude MCP Agent",
    "capabilities": ["read:cap-table", "write:equity", "read:financials"]
  }'

Copy the api_key from the response and use it as OPENCAP_API_KEY.

Option B — Login and use the JWT:

curl -X POST https://api.opencapstack.com/api/v1/auth/login \
  -H "Content-Type: application/json" \
  -d '{"email":"you@example.com","password":"yourpassword"}'

All 29 Tools

Stakeholders (5 tools)

Tool	Description
`list_stakeholders`	List all stakeholders with ownership percentages
`get_stakeholder`	Get a specific stakeholder by ID
`create_stakeholder`	Add a new stakeholder (founder, investor, employee, advisor)
`update_stakeholder`	Update stakeholder details
`delete_stakeholder`	Remove a stakeholder

Tool	Description
`list_share_classes`	List all share classes
`get_share_class`	Get a specific share class
`create_share_class`	Create a new share class (common, preferred, options pool)
`update_share_class`	Update share class terms

Equity Grants (4 tools)

Tool	Description
`list_equity_grants`	List all equity grants
`get_equity_grant`	Get a grant with vesting schedule
`create_equity_grant`	Issue options, RSUs, or warrants
`update_equity_grant`	Update grant status or vesting

SAFE Notes (3 tools)

Tool	Description
`list_safes`	List all SAFE instruments
`get_safe`	Get a SAFE by ID
`create_safe`	Create a new SAFE note

Cap Table (4 tools)

Tool	Description
`cap_table_summary`	Full ownership breakdown by share class and stakeholder
`get_fully_diluted_shares`	Total share count including all options and warrants
`calculate_dilution`	Model ownership impact of a new fundraising round
`run_waterfall_analysis`	Liquidation waterfall for an exit scenario

Valuations (3 tools)

Tool	Description
`get_latest_valuation`	Most recent 409A valuation
`get_valuation_history`	Historical valuation timeline
`create_valuation_request`	Trigger a new 409A valuation

Documents (2 tools)

Tool	Description
`list_documents`	List documents with filtering
`get_document`	Get document metadata and download URL

Financial Reports (2 tools)

Tool	Description
`list_financial_reports`	List generated reports
`create_financial_report`	Generate investor report, cap table summary, or equity ledger

Workflows (2 tools)

Tool	Description
`list_workflows`	List pending approval workflows
`whoami`	Get current authenticated user and company context

Example Conversations

Check ownership

You: What does the cap table look like?

Claude: Let me pull that up.
[calls cap_table_summary]

Here's the current cap table:
- Total issued shares: 12,500,000
- Jane Doe (Founder): 5,000,000 shares — 40%
- Acme Ventures (Series A): 4,500,000 shares — 36%
- Options Pool: 3,000,000 shares — 24%

Issue equity

You: Issue 50,000 options to the new engineer, Alex Kim
     (alex@startup.com), standard 4-year cliff vesting,
     $0.10 strike price.

Claude: I'll create Alex as a stakeholder and issue the grant.
[calls create_stakeholder]
[calls create_equity_grant]

Done. Alex Kim has been added and granted 50,000 options
(Grant #GRANT-AK50000-2026) with a 4-year vest, 1-year cliff,
at $0.10 strike. Vesting starts today.

Model a fundraising round

You: If we raise a $5M Series B at a $20M pre-money,
     what happens to everyone's ownership?

Claude: Running dilution analysis...
[calls calculate_dilution]

Series B dilution impact:
- New shares issued: 2,500,000
- Post-money fully diluted: 16,500,000

After dilution:
- Jane Doe: 40% → 30.3%
- Acme Ventures: 36% → 27.3%
- Series B investors: 0% → 15.2%
- Options Pool: 24% → 18.2% (undiluted)

Run waterfall analysis

You: Model an exit at $30M. Who gets what?

Claude: Running liquidation waterfall...
[calls run_waterfall_analysis]

$30M exit waterfall:
1. Series A 1x liquidation preference: $4.5M → Acme Ventures
2. Remaining $25.5M distributed pro-rata:
   - Jane Doe (40%): $10.2M
   - Acme Ventures (36%): $9.2M
   - Options Pool (24%): $6.1M
Total proceeds: Founders $10.2M, Series A $13.7M

AINative + OpenCap Stack (Combined Setup)

If you use both AINative ZeroDB and OpenCap Stack, configure both MCP servers together:

{
  "mcpServers": {
    "zerodb": {
      "command": "python",
      "args": ["-m", "zerodb_mcp"],
      "env": {
        "ZERODB_API_KEY": "your-zerodb-key",
        "ZERODB_PROJECT_ID": "your-project-id"
      }
    },
    "opencap": {
      "command": "npx",
      "args": ["-y", "@opencapstack/mcp-server"],
      "env": {
        "OPENCAP_API_KEY": "your-opencap-key",
        "OPENCAP_BASE_URL": "https://api.opencapstack.com/api/v1"
      }
    }
  }
}

Now Claude can store memory in ZeroDB and manage your cap table in the same conversation.

Self-Hosted MCP

If you're running OpenCap Stack on your own infrastructure, point the server at your instance:

{
  "env": {
    "OPENCAP_API_KEY": "your-api-key",
    "OPENCAP_BASE_URL": "https://your-opencapstack.company.com/api/v1"
  }
}

See the Self-Hosting guide for deployment instructions.

Setup​

Claude Code​

Cursor​

Windsurf​

Claude Desktop​

Getting Your API Key​

All 29 Tools​

Stakeholders (5 tools)​

Share Classes (4 tools)​

Equity Grants (4 tools)​

SAFE Notes (3 tools)​

Cap Table (4 tools)​

Valuations (3 tools)​

Documents (2 tools)​

Financial Reports (2 tools)​

Workflows (2 tools)​

Example Conversations​

Check ownership​

Issue equity​

Model a fundraising round​

Run waterfall analysis​

AINative + OpenCap Stack (Combined Setup)​

Self-Hosted MCP​