Transports

The heycreo MCP API exposes SSE and Streamable HTTP. Clients that only speak STDIO should use a local bridge (mcp-remote) to those endpoints — the API process does not host an in-process STDIO transport.

SSE (Server-Sent Events)

Endpoint: https://app.heycreo.io/api/sse

The SSE transport opens a persistent connection for server-to-client messages and uses HTTP POST for client-to-server messages. This is the most widely supported transport across MCP clients.

Use when:

• Your client supports SSE (most do: Claude Desktop, Cursor, etc.)
• You want real-time progress updates during long-running operations
• You're building a web-based integration

Streamable HTTP

Endpoint: https://app.heycreo.io/api/mcp

A simpler HTTP-based transport where each tool call is a single HTTP request/response cycle. The response can be streamed.

Use when:

• You prefer stateless request/response communication
• Your environment doesn't support long-lived connections
• You're building a server-side integration

STDIO (via local bridge only)

Transport: local mcp-remote process → remote SSE/HTTP (no API STDIO endpoint)

The API does not register an in-process STDIO transport. Clients that only speak STDIO connect through mcp-remote, which runs as a STDIO process and proxies to https://app.heycreo.io/api/mcp, injecting your auth headers. Claude Desktop and ChatGPT both support the remote endpoint natively via OAuth instead; see Client Examples.

Use when:

• Your client only supports local STDIO servers (bridge to the remote endpoint via mcp-remote)
• You're building a CLI tool or local agent that cannot speak SSE/HTTP directly

Headers (all transports)

Both authentication and organization context are passed via HTTP headers, regardless of transport:

Authorization: Bearer <api_key_or_jwt>
X-heycreo-Org: <organization_slug>

Choosing a transport

Transport	Latency	Streaming	Best for
SSE	Low	Yes	AI clients (Claude, Cursor), web apps
Streamable HTTP	Medium	Yes	Backend integrations, serverless
STDIO	Lowest	No	Local development, CLI tools

For most use cases, SSE is the recommended default.