generated: '2026-09-19'
method: searched
source: openapi/machinelibrary-ai-openapi.yml, openapi/machinelibrary-ai-recognition-openapi.yml (securitySchemes) upgraded with https://api.machinelibrary.ai/auth.md, the RFC 8414 / RFC 9728 metadata under well-known/, https://machinelibrary.ai/privacy (token lifetimes) and the MCP repo README/smithery.yaml (key prefix)
docs: https://api.machinelibrary.ai/auth.md
keys_page: https://machinelibrary.ai/keys
summary:
  types: [apiKey, http, oauth2]
  api_key_in: [header]
  one_credential_three_surfaces: The same API key authenticates the REST API (X-Api-Key or Bearer), the MCP server (Authorization Bearer) and the A2A agent (bearer or X-Api-Key security schemes in the card).
  sign_in_methods: Google, GitHub, or email (press page); the /keys page 302s to /auth/signin for anonymous visitors.
schemes:
- name: api_key
  type: apiKey
  in: header
  parameter: X-Api-Key
  description: Machine Library API key from https://machinelibrary.ai/keys.
  key_prefix: sf_live_ (example shape in the MCP README and smithery.yaml exampleConfig)
  expiry: Long-lived; does not expire automatically, revocable from account settings (privacy policy section 4).
  sources: [openapi/machinelibrary-ai-openapi.yml, openapi/machinelibrary-ai-recognition-openapi.yml]
- name: bearer_auth
  type: http
  scheme: bearer
  bearerFormat: API key or OAuth 2.0 access token
  description: Send the same API key, or an OAuth 2.0 access token, as a Bearer token.
  sources: [openapi/machinelibrary-ai-openapi.yml, openapi/machinelibrary-ai-recognition-openapi.yml]
- name: oauth2
  type: oauth2
  issuer: https://api.spacefrontiers.org
  metadata: https://api.spacefrontiers.org/.well-known/oauth-authorization-server
  protected_resource_metadata:
  - https://mcp.machinelibrary.ai/.well-known/oauth-protected-resource
  - https://machinelibrary.ai/.well-known/oauth-protected-resource
  flows:
    authorizationCode:
      authorizationUrl: https://api.spacefrontiers.org/v2/oauth/authorize
      tokenUrl: https://api.spacefrontiers.org/v2/oauth/token
      refreshUrl: https://api.spacefrontiers.org/v2/oauth/token
      revocationUrl: https://api.spacefrontiers.org/v2/oauth/revoke
      registrationUrl: https://api.spacefrontiers.org/v2/oauth/register
      scopes:
        search: Search the corpus and retrieve research documents using the user's account credits.
      pkce: S256 required
      client_auth: none (public clients; token_endpoint_auth_methods_supported [none])
      resource_indicator: Set the OAuth resource to https://mcp.machinelibrary.ai (auth.md section 7)
    service_auth (agent claim flow):
      description: >-
        For agents that cannot receive a browser callback. POST https://api.spacefrontiers.org/v2/agent/identity
        {"type":"service_auth","login_hint":"<user email>"} returns a registration_id, a secret claim_token and a
        claim {user_code (6 digits), verification_uri, expires_in 900, interval 5}. The user opens the verification
        URI, signs in with the matching verified email, confirms the code and approves; the agent polls the token
        endpoint with grant_type=urn:workos:agent-auth:grant-type:claim&claim_token=... honouring
        authorization_pending / slow_down / access_denied / expired_token. Approval yields a one-hour access_token
        plus a service-signed identity_assertion; renew with grant_type=urn:ietf:params:oauth:grant-type:jwt-bearer&assertion=...
      endpoints:
        identity: https://api.spacefrontiers.org/v2/agent/identity (also served on api.machinelibrary.ai)
        claim: https://api.spacefrontiers.org/v2/agent/identity/claim
        claim_complete: https://api.spacefrontiers.org/v2/agent/identity/claim/complete (browser-only; agents must not call it)
      constraints: Anonymous registration and external identity assertions are not accepted; the email is a login hint, not proof of identity.
  token_lifetimes:
    access_token: 3600 seconds
    refresh_token: 30 days, rotating; reuse of a rotated token revokes the chain
    authorization_code: deleted on exchange or after 60 seconds
  audience_binding: Tokens are audience-bound to the requested MCP host (privacy policy section 4).
  a2a_card_schemes:
    bearer: http bearer — "Machine Library API key or OAuth 2.1 access token"
    apiKey: header X-Api-Key
operation_security:
  default: Every REST operation lists api_key OR bearer_auth (the Recognition operations inherit the same two schemes in the standalone spec); no operation is anonymous except GET /v1/pricing, which answered 200 unauthenticated on 2026-09-19.
  unauthenticated_observations:
  - {url: 'POST https://api.machinelibrary.ai/v2/search/', status: 401, body: '{"detail":"Unauthorized","status":"error"}'}
  - {url: 'POST https://mcp.machinelibrary.ai/ tools/list', status: 401, www_authenticate: 'Bearer resource_metadata="https://mcp.machinelibrary.ai/.well-known/oauth-protected-resource"'}
  - {url: 'POST https://machinelibrary.ai/a2a message/send', status: 200, note: answered with an agent message describing how to authenticate}
  - {url: 'GET https://api.machinelibrary.ai/v1/pricing', status: 200}
safety_rules_from_provider:
- Never ask a user to share a password, session cookie, API key, authorization code, access token, refresh token, claim token, or identity assertion in chat. (auth.md)
- Store claim_token as a secret; show the user only the verification_uri and user_code together; do not email the code. (auth.md)
- Send the access token only to the configured MCP resource. (auth.md)
- On a 401, discard the credential, re-fetch both discovery documents, and restart registration if necessary. (auth.md)