diff --git a/mcp/shared.go b/mcp/shared.go
index 0fc19c5f..f36071de 100644
--- a/mcp/shared.go
+++ b/mcp/shared.go
@@ -269,6 +269,9 @@ func newClientMethodInfo[P paramsPtr[T], R Result, T any](d typedClientMethodHan
 		r := &ClientRequest[P]{Session: s.(*ClientSession)}
 		if p != nil {
 			r.Params = p.(P)
+		} else {
+			r.Params = P(new(T))
+			r.missingParams = true
 		}
 		return r
 	}
@@ -284,6 +287,9 @@ func newServerMethodInfo[P paramsPtr[T], R Result, T any](d typedServerMethodHan
 		r := &ServerRequest[P]{Session: s.(*ServerSession), Extra: re}
 		if p != nil {
 			r.Params = p.(P)
+		} else {
+			r.Params = P(new(T))
+			r.missingParams = true
 		}
 		return r
 	}
@@ -560,15 +566,17 @@ type Request interface {
 
 // A ClientRequest is a request to a client.
 type ClientRequest[P Params] struct {
-	Session *ClientSession
-	Params  P
+	Session       *ClientSession
+	Params        P
+	missingParams bool
 }
 
 // A ServerRequest is a request to a server.
 type ServerRequest[P Params] struct {
-	Session *ServerSession
-	Params  P
-	Extra   *RequestExtra
+	Session       *ServerSession
+	Params        P
+	Extra         *RequestExtra
+	missingParams bool
 }
 
 // RequestExtra is extra information included in requests, typically from
@@ -604,8 +612,30 @@ func (*ServerRequest[P]) isRequest() {}
 func (r *ClientRequest[P]) GetSession() Session { return r.Session }
 func (r *ServerRequest[P]) GetSession() Session { return r.Session }
 
-func (r *ClientRequest[P]) GetParams() Params { return r.Params }
-func (r *ServerRequest[P]) GetParams() Params { return r.Params }
+func (r *ClientRequest[P]) GetParams() Params {
+	if r.missingParams {
+		return nil
+	}
+	return requestParams(r.Params)
+}
+
+func (r *ServerRequest[P]) GetParams() Params {
+	if r.missingParams {
+		return nil
+	}
+	return requestParams(r.Params)
+}
+
+func requestParams[P Params](params P) Params {
+	if any(params) == nil {
+		return nil
+	}
+	value := reflect.ValueOf(params)
+	if value.Kind() == reflect.Ptr && value.IsNil() {
+		return nil
+	}
+	return params
+}
 
 func (r *ClientRequest[P]) GetExtra() *RequestExtra { return nil }
 func (r *ServerRequest[P]) GetExtra() *RequestExtra { return r.Extra }
diff --git a/mcp/shared_test.go b/mcp/shared_test.go
index 1d0ec700..bae46cbd 100644
--- a/mcp/shared_test.go
+++ b/mcp/shared_test.go
@@ -5,6 +5,7 @@
 package mcp
 
 import (
+	"context"
 	"encoding/json"
 	"errors"
 	"strings"
@@ -260,6 +261,82 @@ func TestServerRequest_PerRequestAccessors_Empty(t *testing.T) {
 	}
 }
 
+func TestServerRequestGetParamsMissingOptionalParams(t *testing.T) {
+	info := newServerMethodInfo(
+		func(context.Context, *ServerRequest[*InitializedParams]) (*emptyResult, error) {
+			return &emptyResult{}, nil
+		},
+		missingParamsOK,
+	)
+	params, err := info.unmarshalParams(nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if params != nil {
+		t.Fatalf("unmarshalParams returned %T, want nil", params)
+	}
+
+	req := info.newRequest(&ServerSession{}, params, nil)
+	if got := req.GetParams(); got != nil {
+		t.Fatalf("GetParams() = %T, want nil", got)
+	}
+	typedReq := req.(*ServerRequest[*InitializedParams])
+	if typedReq.Params == nil {
+		t.Fatal("Params field is nil, want zero InitializedParams")
+	}
+	if typedReq.Params.GetMeta() != nil {
+		t.Fatalf("Params.GetMeta() = %v, want nil", typedReq.Params.GetMeta())
+	}
+}
+
+func TestClientRequestMissingOptionalParamsUsesZeroValue(t *testing.T) {
+	info := newClientMethodInfo(
+		func(context.Context, *ClientRequest[*PingParams]) (*emptyResult, error) {
+			return &emptyResult{}, nil
+		},
+		missingParamsOK,
+	)
+	params, err := info.unmarshalParams(nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if params != nil {
+		t.Fatalf("unmarshalParams returned %T, want nil", params)
+	}
+
+	req := info.newRequest(&ClientSession{}, params, nil)
+	if got := req.GetParams(); got != nil {
+		t.Fatalf("GetParams() = %T, want nil", got)
+	}
+	typedReq := req.(*ClientRequest[*PingParams])
+	if typedReq.Params == nil {
+		t.Fatal("Params field is nil, want zero PingParams")
+	}
+	if typedReq.Params.GetMeta() != nil {
+		t.Fatalf("Params.GetMeta() = %v, want nil", typedReq.Params.GetMeta())
+	}
+}
+
+func TestRequestGetParamsTypedNilCustomParams(t *testing.T) {
+	type customParams struct{ ParamsBase }
+
+	var params *customParams
+	if got := (&ClientRequest[*customParams]{Params: params}).GetParams(); got != nil {
+		t.Fatalf("client GetParams() = %T, want nil", got)
+	}
+	if got := (&ServerRequest[*customParams]{Params: params}).GetParams(); got != nil {
+		t.Fatalf("server GetParams() = %T, want nil", got)
+	}
+
+	params = &customParams{}
+	if got := (&ClientRequest[*customParams]{Params: params}).GetParams(); got != params {
+		t.Fatalf("client GetParams() = %T, want original params", got)
+	}
+	if got := (&ServerRequest[*customParams]{Params: params}).GetParams(); got != params {
+		t.Fatalf("server GetParams() = %T, want original params", got)
+	}
+}
+
 func TestImplementationDescriptionJSON(t *testing.T) {
 	impl := &Implementation{
 		Name:        "greeter",