MCP vs API
Same trusted engine. Different way of asking.
MCP is the protocol surface for AI agents. REST is the direct surface for applications. Both delegate chart calculations to the same HumanDesign.ai authority, but their credentials and available operations differ.
| Question | MCP | REST API |
|---|---|---|
| Who chooses the operation? | The AI client discovers and selects an allowed tool. | Your application calls an explicit route. |
| Surface | JSON-RPC POST at https://mcp.humandesign.ai/. | A complete catalog of HTTP endpoints. |
| Authentication | OAuth for private account tools; API keys for the six calculation tools. | API key for application calculations. |
| Best for | Claude, ChatGPT, Codex, Cursor, VS Code, and custom agents. | Web apps, mobile apps, automations, and data pipelines. |
| Coverage | Membership-filtered account tools or six API-key calculation tools. | Charts, forecasts, returns, calendars, batch operations, and more. |
| Usage | Discovery and eligible reads are free; provider-reaching calculations report their quota effect. | Billed calculations use the same authoritative API quota system. |
Choose MCP when…
An agent should inspect versioned schemas, choose among allowed tools, and call them inside a conversational workflow.
Connect MCPChoose REST when…
Your code already knows the calculation it needs, or you need the broader endpoint catalog.
Explore REST