MCP Transport Auto-Detection

The MCP class reads your connection string and picks the right transport automatically — you never set a transport flag.

from praisonaiagents import Agent, MCP

agent = Agent(
    name="Assistant",
    instructions="You help users with external tools.",
    tools=MCP("https://api.example.com/mcp"),  # transport auto-detected
)

agent.start("Use the available tools to help me.")

The user passes one URL; the agent connects over Streamable HTTP because the URL is http(s):// with a path.

Quick Start

Streamable HTTP (path required)

from praisonaiagents import Agent, MCP

agent = Agent(
    tools=MCP("https://api.example.com/mcp")
)

stdio, SSE, or WebSocket

from praisonaiagents import Agent, MCP

# stdio subprocess
agent = Agent(tools=MCP("npx @modelcontextprotocol/server-memory"))

# Legacy SSE (URL ends in /sse)
agent = Agent(tools=MCP("http://localhost:8080/sse"))

# WebSocket
agent = Agent(tools=MCP("wss://api.example.com/mcp"))

Detection Rules

The MCP class routes URL classification through a single helper, get_transport_type, so every transport follows the same rules.

URL Pattern	Transport	Example
`ws://` or `wss://`	WebSocket	`ws://localhost:8080/mcp`
`http(s)://...` ending in `/sse`	SSE (Legacy)	`http://localhost:8080/sse`
`http(s)://<host><path>` (path required)	Streamable HTTP	`https://api.example.com/mcp`
Command string	stdio	`npx @mcp/server-memory`

For Streamable HTTP, the URL is used verbatim — include the endpoint path your server exposes (commonly /mcp). A bare-host URL will POST to / and fail with Session terminated. See PraisonAI #3032.

How It Works

The helper checks the URL scheme and suffix in order, then defaults to stdio for anything that is not a URL.

Check	Result
Matches `wss?://`	`websocket`
Matches `https?://` and ends in `/sse`	`sse`
Matches `https?://` with any other path	`http_stream`
Anything else	`stdio`

Common Patterns

Override auto-detection only when you must — pass a URL that already fits the transport you want.

from praisonaiagents import Agent, MCP

# Force legacy SSE by using a /sse URL
agent = Agent(tools=MCP("http://localhost:8080/sse"))

# Force Streamable HTTP by including a path
agent = Agent(tools=MCP("https://api.example.com/mcp"))

Best Practices

Always include a path for HTTP servers

A bare https://host POSTs to / and fails with Session terminated. Pass the full endpoint, commonly /mcp.

Use /sse only for legacy servers

URLs ending in /sse select the deprecated SSE transport. Prefer Streamable HTTP for new servers.

Use ws:// or wss:// for real-time

WebSocket is auto-detected from the scheme and suits long-lived, bidirectional connections.

Command strings default to stdio

Anything that is not a URL runs as a local subprocess over stdio.

MCP Transports

Full guide to each transport

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MCP Transport Auto-Detection

Quick Start

Detection Rules

How It Works

Common Patterns

Best Practices

MCP Transports

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​Quick Start

​Detection Rules

​How It Works

​Common Patterns

​Best Practices

​Related

MCP Transports

MCP Integration

Quick Start

Detection Rules

How It Works

Common Patterns

Best Practices

Related