Update capabilities to be expressible by Boolean literals (modelcontextprotocol#16)

* Conform Server.Capabilities types to ExpressibleByBooleanLiteral

* Conform Client.Capabilities types to ExpressibleByBooleanLiteral

* Use Boolean literatls for capabilities in tests

* Update README

Author: mattt

README.md

@@ -51,11 +51,9 @@ let server = Server(
     name: "MyServer", 
     version: "1.0.0",
     capabilities: .init(
-        prompts: .init(),
-        resources: .init(
-            subscribe: true
-        ),
-        tools: .init()
+        prompts: true,
+        resources: true,
+        tools: true
     )
 )
 

Sources/MCP/Client/Client.swift

@@ -408,3 +408,17 @@ public actor Client {
         return value
     }
 }
+
+// MARK: - ExpressibleByBooleanLiteral
+
+extension Client.Capabilities.Roots: ExpressibleByBooleanLiteral {
+    public init(booleanLiteral value: Bool) {
+        self.init()
+    }
+}
+
+extension Client.Capabilities.Sampling: ExpressibleByBooleanLiteral {
+    public init(booleanLiteral value: Bool) {
+        self.init()
+    }
+}

Sources/MCP/Server/Server.swift

@@ -408,3 +408,29 @@ public actor Server {
         self.isInitialized = true
     }
 }
+
+// MARK: - ExpressibleByBooleanLiteral
+
+extension Server.Capabilities.Logging: ExpressibleByBooleanLiteral {
+    public init(booleanLiteral value: Bool) {
+        self.init()
+    }
+}
+
+extension Server.Capabilities.Prompts: ExpressibleByBooleanLiteral {
+    public init(booleanLiteral value: Bool) {
+        self.init()
+    }
+}
+
+extension Server.Capabilities.Resources: ExpressibleByBooleanLiteral {
+    public init(booleanLiteral value: Bool) {
+        self.init()
+    }
+}
+
+extension Server.Capabilities.Tools: ExpressibleByBooleanLiteral {
+    public init(booleanLiteral value: Bool) {
+        self.init()
+    }
+}

Tests/MCPTests/RoundtripTests.swift

@@ -34,9 +34,9 @@ struct RoundtripTests {
             name: "TestServer",
             version: "1.0.0",
             capabilities: .init(
-                prompts: .init(),
-                resources: .init(),
-                tools: .init()
+                prompts: true,
+                resources: true,
+                tools: true
             )
         )
         await server.withMethodHandler(ListTools.self) { _ in