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mcp: Deprecate roots, sampling and logging (SEP-2577) (#1017)

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Fixes #1013
This commit is contained in:
Guglielmo Colombo 2026-06-23 11:11:08 +02:00 • committed by GitHub
commit b6649db4f9
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1 changed files with 320 additions and 25 deletions
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49
mcp/server.go
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@ -73,6 +73,12 @@ type ServerOptions struct {
// If zero, defaults to [DefaultPageSize].
PageSize int
// If non-nil, called when "notifications/roots/list_changed" is received.
//
// Deprecated: the roots feature is deprecated as of protocol version
// 2026-07-28 (SEP-2577). It remains functional during the deprecation
// window (at least twelve months). Migrate to passing paths via tool
// parameters, resource URIs, or configuration. See
// https://modelcontextprotocol.io/seps/2577-deprecate-roots-sampling-and-logging.
RootsListChangedHandler func(context.Context, *RootsListChangedRequest)
// If non-nil, called when "notifications/progress" is received.
ProgressNotificationHandler func(context.Context, *ProgressNotificationServerRequest)
@ -1474,6 +1480,12 @@ func (ss *ServerSession) Ping(ctx context.Context, params *PingParams) error {
}
// ListRoots lists the client roots.
//
// Deprecated: the roots feature is deprecated as of protocol version
// 2026-07-28 (SEP-2577). It remains functional during the deprecation window
// (at least twelve months). Migrate to passing paths via tool parameters,
// resource URIs, or configuration. See
// https://modelcontextprotocol.io/seps/2577-deprecate-roots-sampling-and-logging.
func (ss *ServerSession) ListRoots(ctx context.Context, params *ListRootsParams) (*ListRootsResult, error) {
if err := ss.checkInitialized(methodListRoots); err != nil {
return nil, err
@ -1486,6 +1498,12 @@ func (ss *ServerSession) ListRoots(ctx context.Context, params *ListRootsParams)
// If the client returns multiple content blocks (e.g. parallel tool calls),
// CreateMessage returns an error. Use [ServerSession.CreateMessageWithTools]
// for tool-enabled sampling.
//
// Deprecated: the sampling feature is deprecated as of protocol version
// 2026-07-28 (SEP-2577). It remains functional during the deprecation window
// (at least twelve months). Migrate to calling LLM provider APIs directly
// from your server. See
// https://modelcontextprotocol.io/seps/2577-deprecate-roots-sampling-and-logging.
func (ss *ServerSession) CreateMessage(ctx context.Context, params *CreateMessageParams) (*CreateMessageResult, error) {
if err := ss.checkInitialized(methodCreateMessage); err != nil {
return nil, err
@ -1523,6 +1541,12 @@ func (ss *ServerSession) CreateMessage(ctx context.Context, params *CreateMessag
// returning a [CreateMessageWithToolsResult] that supports array content
// (for parallel tool calls). Use this instead of [ServerSession.CreateMessage]
// when the request includes tools.
//
// Deprecated: the sampling feature is deprecated as of protocol version
// 2026-07-28 (SEP-2577). It remains functional during the deprecation window
// (at least twelve months). Migrate to calling LLM provider APIs directly
// from your server. See
// https://modelcontextprotocol.io/seps/2577-deprecate-roots-sampling-and-logging.
func (ss *ServerSession) CreateMessageWithTools(ctx context.Context, params *CreateMessageWithToolsParams) (*CreateMessageWithToolsResult, error) {
if err := ss.checkInitialized(methodCreateMessage); err != nil {
return nil, err
@ -1609,28 +1633,21 @@ func (ss *ServerSession) Elicit(ctx context.Context, params *ElicitParams) (*Eli
return res, nil
}
// logLevelContextKey carries the per-request log level from
// [ServerSession.handle] to [ServerSession.Log] for new-protocol
// (>= 2026-07-28) requests. The level is scoped to a single in-flight request
// — including handler goroutines that call [ServerSession.Log] concurrently —
// rather than to the session, which avoids races between concurrent requests
// and aligns with SEP-2575's per-request opt-in model. The value type is
// [LoggingLevel]; an empty string means the request opted out of log messages.
type logLevelContextKey struct{}
// Log sends a log message to the client.
//
// For new-protocol (>= 2026-07-28) requests, the level is taken from the
// originating request's `_meta` field (SEP-2575); an absent or empty value
// suppresses the message per spec. For old-protocol requests, the level is
// taken from the session state set via `logging/setLevel`.
//
// Deprecated: the logging feature is deprecated as of protocol version
// 2026-07-28 (SEP-2577). It remains functional during the deprecation window
// (at least twelve months). See
// https://modelcontextprotocol.io/seps/2577-deprecate-roots-sampling-and-logging.
func (ss *ServerSession) Log(ctx context.Context, params *LoggingMessageParams) error {
logLevel, ok := ctx.Value(logLevelContextKey{}).(LoggingLevel)
if !ok {
ss.mu.Lock()
logLevel = ss.state.LogLevel
ss.mu.Unlock()
}
ss.mu.Lock()
logLevel := ss.state.LogLevel
ss.mu.Unlock()
if logLevel == "" {
// The spec is unclear, but seems to imply that no log messages are sent until the client
// sets the level.
@ -1806,7 +1823,7 @@ func (ss *ServerSession) handle(ctx context.Context, req *jsonrpc.Request) (any,
ctx = context.WithValue(ctx, idContextKey{}, req.ID)
// For new-protocol requests, propagate the per-request log level.
if validatedMeta.usesNewProtocol {
ctx = context.WithValue(ctx, logLevelContextKey{}, validatedMeta.logLevel)
ss.setLevel(ctx, &SetLoggingLevelParams{Level: validatedMeta.logLevel})
}
return handleReceive(ctx, ss, req)
}