> ## Documentation Index
> Fetch the complete documentation index at: https://praison.ai/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# MCP Transport Auto-Detection

> How the MCP class picks stdio, SSE, Streamable HTTP, or WebSocket from your URL

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

```python theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
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.

```mermaid theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
graph TB
    URL[🔗 Connection String] --> Check{Match pattern?}
    Check -->|ws:// or wss://| WS[🔌 WebSocket]
    Check -->|http s :// ending in /sse| SSE[📡 SSE Legacy]
    Check -->|http s :// with path| HTTP[🌐 Streamable HTTP]
    Check -->|anything else| STDIO[📟 stdio subprocess]

    classDef input fill:#8B0000,stroke:#7C90A0,color:#fff
    classDef decision fill:#F59E0B,stroke:#7C90A0,color:#fff
    classDef transport fill:#189AB4,stroke:#7C90A0,color:#fff

    class URL input
    class Check decision
    class WS,SSE,HTTP,STDIO transport
```

## Quick Start

<Steps>
  <Step title="Streamable HTTP (path required)">
    ```python theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
    from praisonaiagents import Agent, MCP

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

  <Step title="stdio, SSE, or WebSocket">
    ```python theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
    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"))
    ```
  </Step>
</Steps>

***

## 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`      |

<Note>
  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](https://github.com/MervinPraison/PraisonAI/issues/3032).
</Note>

***

## How It Works

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

```mermaid theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
sequenceDiagram
    participant User
    participant MCP as MCP Class
    participant Helper as get_transport_type

    User->>MCP: MCP("https://api.example.com/mcp")
    MCP->>Helper: classify URL
    Helper-->>MCP: "http_stream"
    MCP-->>User: Streamable HTTP client ready
```

| 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.

```python theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
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

<AccordionGroup>
  <Accordion title="Always include a path for HTTP servers">
    A bare `https://host` POSTs to `/` and fails with `Session terminated`. Pass the full endpoint, commonly `/mcp`.
  </Accordion>

  <Accordion title="Use /sse only for legacy servers">
    URLs ending in `/sse` select the deprecated SSE transport. Prefer Streamable HTTP for new servers.
  </Accordion>

  <Accordion title="Use ws:// or wss:// for real-time">
    WebSocket is auto-detected from the scheme and suits long-lived, bidirectional connections.
  </Accordion>

  <Accordion title="Command strings default to stdio">
    Anything that is not a URL runs as a local subprocess over stdio.
  </Accordion>
</AccordionGroup>

***

## Related

<CardGroup cols={2}>
  <Card title="MCP Transports" icon="network-wired" href="/docs/mcp/transports">
    Full guide to each transport
  </Card>

  <Card title="MCP Integration" icon="plug" href="/docs/features/mcp">
    Connect agents to MCP servers
  </Card>
</CardGroup>