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Merged
dsp-ant merged 3 commits into from
Jun 6, 2025
Merged

move version header doc to transports #658

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93a8b11
move version header doc to transports
bhosmer-ant Jun 6, 2025
a11c843
format
bhosmer-ant Jun 6, 2025
6ab271d
Merge branch 'main' into basil/version_header_in_shttp
dsp-ant Jun 6, 2025
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13 changes: 5 additions & 8 deletions docs/specification/draft/basic/lifecycle.mdx
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Expand Up @@ -138,15 +138,12 @@ supports. This **SHOULD** be the _latest_ version supported by the server.
If the client does not support the version in the server's response, it **SHOULD**
disconnect.

<Note>
If using HTTP, the client **MUST** include the `MCP-Protocol-Version:
<protocol-version>` HTTP header during any subsequent requests to the MCP
server, allowing the MCP server to respond based on the MCP protocol version.

The protocol version sent by the client **SHOULD** be the one negotiated during [initialization](https://modelcontextprotocol.io/specification/draft/basic/lifecycle#initialization).

If the server receives a request with a missing, invalid, or unsupported
MCP-Protocol-VERSION, it **MUST** respond with `400 Bad Request`.
For example: `MCP-Protocol-Version: 2024-11-05`
<protocol-version>` HTTP header on all subsequent requests to the MCP
server.
For details, see [the Protocol Version Header section in Transports](/specification/draft/basic/transports#protocol-version-header).
</Note>

#### Capability Negotiation

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14 changes: 14 additions & 0 deletions docs/specification/draft/basic/transports.mdx
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Expand Up @@ -237,6 +237,20 @@ sequenceDiagram

```

### Protocol Version Header

If using HTTP, the client **MUST** include the `MCP-Protocol-Version:
<protocol-version>` HTTP header on all subsequent requests to the MCP
server, allowing the MCP server to respond based on the MCP protocol version.

The protocol version sent by the client **SHOULD** be the one [negotiated during
initialization](/specification/draft/basic/lifecycle#version-negotiation).

For example: `MCP-Protocol-Version: 2025-03-26`

If the server receives a request with a missing, invalid, or unsupported
MCP-Protocol-VERSION, it **MUST** respond with `400 Bad Request`.

### Backwards Compatibility

Clients and servers can maintain backwards compatibility with the deprecated [HTTP+SSE
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