feat: intermediate updates to newest protocol

Sources/MCP/Base/Annotations.swift

@@ -0,0 +1,40 @@
+import Foundation
+
+/// The sender or recipient of messages and data in a conversation.
+public enum Role: String, Hashable, Codable, Sendable {
+    /// A user message
+    case user
+    /// An assistant message
+    case assistant
+}
+
+/// Optional annotations for content, used to inform how objects are used or displayed.
+///
+/// - SeeAlso: https://modelcontextprotocol.io/specification/2025-11-25/schema#annotations
+public struct Annotations: Hashable, Codable, Sendable {
+    // TODO: Deprecate in a future version
+    /// Backwards compatibility alias for top-level `Role`.
+    public typealias Role = MCP.Role
+
+    /// Describes who the intended audience of this object or data is.
+    /// It can include multiple entries to indicate content useful for multiple audiences.
+    public var audience: [Role]?
+
+    /// Describes how important this data is for operating the server.
+    /// A value of 1 means "most important" (effectively required),
+    /// while 0 means "least important" (entirely optional).
+    public var priority: Double?
+
+    /// The moment the resource was last modified, as an ISO 8601 formatted string.
+    public var lastModified: String?
+
+    public init(
+        audience: [Role]? = nil,
+        priority: Double? = nil,
+        lastModified: String? = nil
+    ) {
+        self.audience = audience
+        self.priority = priority
+        self.lastModified = lastModified
+    }
+}