---
title: "Use Streamable HTTP only where supported"
description: "Streamable HTTP is not defined by the earliest supported MCP protocol version. Scope the transport to versions that define it and keep root protocol coverage consistent. A URL alon"
source: "https://mcpdesc.org/docs/rules/0.9.0-rc.3/mcp/transport-streamable-http-protocol-version/"
---

Streamable HTTP is not defined by the earliest supported MCP protocol version. Scope the transport to versions that define it and keep root protocol coverage consistent. A URL alone does not make a transport applicable to every protocol version.

## Requirement

Streamable HTTP is used only from MCP 2025-03-26.

## Details

**Rule ID:** `mcp.transport.streamable-http.protocol-version`  
**Owner:** mcp  
**Surface:** Transport  
**Kind:** structural  
**Requirement level:** must  
**Status:** internal · **Enforcement:** internal

## Protocol version applicability

| 2024-11-05 | 2025-03-26 | 2025-06-18 | 2025-11-25 | 2026-07-28 |
| ---------- | ---------- | ---------- | ---------- | ---------- |
| applies    | applies    | applies    | applies    | applies    |

## Required by

* **MCP Description 0.9.0, Section 6.2**  
  * 6\. Transports: [req-transport-streamable-http-protocol-versions](https://mcpdesc.org/docs/specification/0.9.0-rc.3/transports#req-transport-streamable-http-protocol-versions)

## Based on

* **Tier 1 — MCP schema.ts and normative specification text:** MCP 2025-03-26 specification, Basic, Transports, Streamable HTTP (replaces HTTP+SSE from 2024-11-05)  
  * <https://github.com/modelcontextprotocol/modelcontextprotocol/blob/dae694f61a31f7a3ec2af3aff709e11f70f61e48/docs/specification/2025-03-26/basic/transports.mdx#L50-L277>

## Examples

### Invalid example

Source: [expected-invalid/protocol-version-inapplicable-streamable-http.json](https://github.com/mcpdesc/mcpdesc-specification/blob/v0.9.0-rc.3/spec/draft/fixtures/expected-invalid/protocol-version-inapplicable-streamable-http.json) · Selected: `/transports/0`

```json
{
  "type": "streamable-http",
  "url": "https://example.com/mcp"
}
```

## Rule Source Code

[transport.yaml](https://github.com/mcpdesc/mcpdesc-specification/blob/v0.9.0-rc.3/spec/draft/validation/rules/transport.yaml) at immutable tag [v0.9.0-rc.3](https://github.com/mcpdesc/mcpdesc-specification/blob/v0.9.0-rc.3/spec/draft).