generated: '2026-07-19'
method: searched
status: published
source: https://docs.horizon3.ai/portal/features/mcp/h3_hosted/
server:
  name: horizon3ai
  vendor: Horizon3.ai
  transport: streamable-http
  description: Horizon3.ai-hosted Model Context Protocol server exposing NodeZero data and actions to
    MCP-compliant agents. Backs onto the same NodeZero platform as the GraphQL API. Secured with OAuth
    2.1 (PKCE) via oauth-proxy.horizon3ai.com; tokens are short-lived JWTs expiring after 1 hour.
  endpoints:
  - region: US
    url: https://mcp.horizon3ai.com/mcp
  - region: EU
    url: https://mcp.horizon3ai.eu/mcp
  - region: FedRAMP High
    url: https://mcp.gov-horizon3ai.com/mcp
  auth:
    type: oauth2.1
    flow: authorization_code
    pkce: S256
    authorization_server: https://oauth-proxy.horizon3ai.com
    authorization_endpoint: https://oauth-proxy.horizon3ai.com/authorize
    token_endpoint: https://oauth-proxy.horizon3ai.com/token
    registration_endpoint: https://oauth-proxy.horizon3ai.com/register
    scopes:
    - read
    - write
    redirect_uris: loopback (localhost / 127.0.0.1, any port)
    token_ttl_seconds: 3600
  well_known:
  - well-known/horizon3ai-mcp-oauth-authorization-server.json
  - well-known/horizon3ai-mcp-oauth-protected-resource.json
  - well-known/horizon3ai-mcp-openid-configuration.json
  clients_supported:
  - VS Code
  - Claude Code
  - Gemini CLI
  - Windsurf
notes: 'Official, published, hosted remote MCP server. Tool inventory is not enumerated in the public
  setup docs; access is gated behind Portal OAuth login. Setup: MCP: Add Server -> HTTP transport -> regional
  URL -> OAuth redirect to the Horizon3 Portal.'
deployment:
  mode: remote
  endpoint: https://mcp.horizon3ai.com/mcp
  verified: probed
  probe: gated
  checked: '2026-09-11'
  source: wall re-adjudication 2026-09-11 (RFC 9728 / JSON-RPC envelope)
  probe_prior: wall
  probe_why: RFC 9728 challenge (host-wide OAuth-protected resource)