diff --git a/Sources/MCP/Server/Tools.swift b/Sources/MCP/Server/Tools.swift
index 9c08b72..edfe112 100644
--- a/Sources/MCP/Server/Tools.swift
+++ b/Sources/MCP/Server/Tools.swift
@@ -14,7 +14,7 @@ public struct Tool: Hashable, Codable, Sendable {
     /// The tool description
     public let description: String
     /// The tool input schema
-    public let inputSchema: Value?
+    public let inputSchema: Value
 
     /// Annotations that provide display-facing and operational information for a Tool.
     ///
@@ -86,7 +86,7 @@ public struct Tool: Hashable, Codable, Sendable {
     public init(
         name: String,
         description: String,
-        inputSchema: Value? = nil,
+        inputSchema: Value,
         annotations: Annotations = nil
     ) {
         self.name = name
@@ -183,7 +183,7 @@ public struct Tool: Hashable, Codable, Sendable {
         let container = try decoder.container(keyedBy: CodingKeys.self)
         name = try container.decode(String.self, forKey: .name)
         description = try container.decode(String.self, forKey: .description)
-        inputSchema = try container.decodeIfPresent(Value.self, forKey: .inputSchema)
+        inputSchema = try container.decode(Value.self, forKey: .inputSchema)
         annotations =
             try container.decodeIfPresent(Tool.Annotations.self, forKey: .annotations) ?? .init()
     }
@@ -192,9 +192,7 @@ public struct Tool: Hashable, Codable, Sendable {
         var container = encoder.container(keyedBy: CodingKeys.self)
         try container.encode(name, forKey: .name)
         try container.encode(description, forKey: .description)
-        if let schema = inputSchema {
-            try container.encode(schema, forKey: .inputSchema)
-        }
+        try container.encode(inputSchema, forKey: .inputSchema)
         if !annotations.isEmpty {
             try container.encode(annotations, forKey: .annotations)
         }
diff --git a/Tests/MCPTests/ToolTests.swift b/Tests/MCPTests/ToolTests.swift
index 981c546..af48f3e 100644
--- a/Tests/MCPTests/ToolTests.swift
+++ b/Tests/MCPTests/ToolTests.swift
@@ -130,7 +130,8 @@ struct ToolTests {
     func testToolWithEmptyAnnotations() throws {
         var tool = Tool(
             name: "test_tool",
-            description: "Test tool description"
+            description: "Test tool description",
+            inputSchema: [:]
         )
 
         do {
@@ -163,7 +164,7 @@ struct ToolTests {
         let tool = Tool(
             name: "test_tool",
             description: "Test tool description",
-            inputSchema: nil,
+            inputSchema: [:],
             annotations: nil
         )
 
@@ -324,8 +325,8 @@ struct ToolTests {
     @Test("ListTools result validation")
     func testListToolsResult() throws {
         let tools = [
-            Tool(name: "tool1", description: "First tool", inputSchema: nil),
-            Tool(name: "tool2", description: "Second tool", inputSchema: nil),
+            Tool(name: "tool1", description: "First tool", inputSchema: [:]),
+            Tool(name: "tool2", description: "Second tool", inputSchema: [:]),
         ]
 
         let result = ListTools.Result(tools: tools, nextCursor: "next_page")
@@ -399,7 +400,11 @@ struct ToolTests {
             #expect(request.id == 1)
             #expect(request.params.cursor == nil)
 
-            let testTool = Tool(name: "test_tool", description: "Test tool for verification")
+            let testTool = Tool(
+                name: "test_tool",
+                description: "Test tool for verification",
+                inputSchema: [:]
+            )
             return ListTools.response(id: request.id, result: ListTools.Result(tools: [testTool]))
         }