modelcontextprotocol/go-sdk
Watch
1
0
Fork
You've already forked go-sdk
 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions 1

mcp: add documentation for new protocol version (#1019)

Browse source 
Add documentation for new protocol version in the `internal/docs`
This commit is contained in:
Guglielmo Colombo 2026-06-23 17:07:38 +02:00 • committed by GitHub
commit b9e6fc5a66
No known key found for this signature in database
GPG key ID: B5690EEEBB952194
1 changed files with 719 additions and 36 deletions
Download patch file Download diff file Expand all files Collapse all files

53
internal/docs/client.src.md
View file

@ -28,6 +28,10 @@ client, a call to `AddRoot` or `RemoveRoots` will result in a
[`ServerSession.ListRoots`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#ServerSession.ListRoots)
method. To receive notifications about root changes, set
[`ServerOptions.RootsListChangedHandler`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#ServerOptions.RootsListChangedHandler).
For protocol versions `2026-07-28` and later, `ListRoots` requests are
delivered via the
[Multi Round-Trip Requests](protocol.md#multi-round-trip-requests-mrtr)
pattern.
%include ../../mcp/client_example_test.go roots -
@ -51,6 +55,11 @@ This function is invoked whenever the server requests sampling.
**Server-side**: To use sampling from the server, call
[`ServerSession.CreateMessage`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#ServerSession.CreateMessage).
For protocol versions `2026-07-28` and later, sampling requests are
delivered via the
[Multi Round-Trip Requests](protocol.md#multi-round-trip-requests-mrtr)
pattern.
%include ../../mcp/client_example_test.go sampling -
## Elicitation
@ -68,8 +77,44 @@ you must declare that capability explicitly (see [Capabilities](#capabilities))
**Server-side**: To use elicitation from the server, call
[`ServerSession.Elicit`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#ServerSession.Elicit).
For protocol versions `2026-07-28` and later, elicitation requests are
delivered via the
[Multi Round-Trip Requests](protocol.md#multi-round-trip-requests-mrtr)
pattern.
%include ../../mcp/client_example_test.go elicitation -
## Multi Round-Trip Requests (MRTR)
[SEP-2322](https://github.com/modelcontextprotocol/modelcontextprotocol/pull/2322)
introduces the MRTR pattern: server-to-client requests for sampling,
elicitation, and roots are no longer issued as fresh JSON-RPC requests but
are carried inside the in-flight reply of a `tools/call`, `prompts/get`, or
`resources/read`. The client must respond by retrying the original request
with the produced responses.
The SDK installs `clientMultiRoundTripMiddleware` for every client by
default. The middleware:
1. Inspects each `tools/call`/`prompts/get`/`resources/read` reply.
2. If the result's `NeedsInput()` is true, fans out the `InputRequests` map
concurrently, calling the configured handler for each (`elicit`,
`createMessage`/`createMessageWithTools`, or `listRoots`).
3. Threads the server-supplied opaque `RequestState` back unchanged.
4. Retries the original request with the responses set, repeating until the
result no longer needs input.
The middleware is enabled by default. To opt out, set
[`ClientOptions.MultiRoundTrip.Disabled = true`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#MultiRoundTripOptions);
the client will then surface `InputRequiredResult` values directly to the
caller and your code must fulfil the requests manually.
For legacy (`<= 2025-11-25`) servers, the SDK transparently sends server
requests on the legacy server-initiated channel; the MRTR machinery is a
no-op in that direction. For legacy clients talking to MRTR-style servers,
the server SDK applies the inverse compatibility shim — see the
[server-side documentation](server.md#multi-round-trip-requests-mrtr).
## Capabilities
Client capabilities are advertised to servers during the initialization
@ -126,3 +171,11 @@ client := mcp.NewClient(impl, &mcp.ClientOptions{
})
```
### Extensions
[SEP-2133](https://github.com/modelcontextprotocol/modelcontextprotocol/pull/2133)
adds an `extensions` map to `ClientCapabilities` and `ServerCapabilities` so
that optional capabilities outside the core protocol can be declared on the
wire. Keys are namespaced as `"{vendor-prefix}/{extension-name}"`; values
are per-extension settings objects.