Configuration

Neither package reads the environment or the filesystem. Your application does, and passes the values in. These variables configure the MCP server box in Deployment.

Variable	Purpose
MCP_PUBLIC_URL	URL Claude reaches
OAUTH_ISSUER	Authorization server issuer
OAUTH_AUTHORIZATION_ENDPOINT	From AS metadata
OAUTH_TOKEN_ENDPOINT	Same
OAUTH_REGISTRATION_ENDPOINT	Optional; needed if clients still use DCR
OAUTH_JWKS_URI	Signing keys
GOOGLE_WORKSPACE_DOMAIN	Optional. Refuse tokens outside your domain
MCP_POLICY	Optional. Policy JSON, when not written in code

Every value except the last two comes off your authorization server. Pass OAUTH_ISSUER alone to discoverOAuth and it reads the endpoints and jwks_uri for you.

Configure the AS itself first. The ordered steps are in Point your AS at it.

Policy from the environment

MCP_POLICY='{"roles":{"reader":["cases:read"]},
             "rules":[{"match":{"domain":"acme.com"},"role":"reader"}]}'

const policy = definePolicy(JSON.parse(process.env.MCP_POLICY!));

The shape is still validated and the catalogue is still reconciled at boot. Permission names lose their compile-time check, because TypeScript never saw them. YAML you parsed yourself works the same way.