Platform via MCP and API
REST for multi-tenant partner sends. MCP for single-user agent workflows.
REST (partners)
- Use a platform API key.
- Add
Atlas-Account: ext_<external_id>on every envelope and template call.
Key routes: POST /api/platform/connected-accounts, POST /api/envelope, POST /api/envelope/{id}/send, POST /api/templates/{id}/send.
OpenAPI: openapi.json
MCP (agents)
- MCP is user-scoped in v1. No
Atlas-Accountparameter. - Your team can use all 10 MCP tools for their own org.
- Pass
team_idwhen the user has multiple teams.
When to use which
| MCP | REST |
|---|---|
| Human sends from Claude or ChatGPT | Backend sends for many clients |
| One workspace per user | Provision connected accounts via API |
OAuth (ChatGPT) is user-scoped like MCP. Do not use OAuth for connected-account sends.