plain.com
Plain is a customer support platform for managing support threads, customers, help center content, and related workflows. It also supports AI-assisted and custom agent workflows that operate on support data in a Plain workspace.
plain.com exposes a GraphQL API at `core-api.uk.plain.com/graphql/v1` authenticated with machine-user API keys, plus a remote MCP server at `mcp.plain.com/mcp` authenticated with Plain account OAuth.
- Plain MCP serverdetected
- Plain GraphQL APIdiscovered
In Plain, go to Settings → Machine Users, create or open a machine user, then click Add API Key and choose the permissions you need. Copy the key when it is shown; the docs note you will not be able to see it again after leaving the page. Use it as Authorization: Bearer plainApiKey_xxx. See Authentication and Machine users.
Point your MCP client at the server URL and approve access in the browser. The server accepts a Client ID Metadata Document (CIMD), so the client authenticates with its own hosted URL as the client_id — nothing to register.
conventions · 1/8 published
- integrations.json✗
/.well-known/integrations.json - llms.txt✓https://plain.com/llms.txt
- API catalog✗
/.well-known/api-catalog - OpenAPI document✗
/api/schema/, /openapi.json, /swagger.json, /api/openapi.json, or /v1/openapi.json - MCP server card✗
/.well-known/mcp/server-card.json - OAuth protected resource✗
/.well-known/oauth-protected-resource - Agent card✗
/.well-known/agent-card.json - Agent skills✗
/.well-known/agent-skills/index.json
Publish these signals → /publishing