diff --git a/build.sbt b/build.sbt
index 146d9de..7179546 100644
--- a/build.sbt
+++ b/build.sbt
@@ -17,7 +17,7 @@ lazy val Versions = new {
   val jackson = "2.20.0"
   val tapir = "1.11.42"
   val jsonSchemaCirce = "0.11.10"
-  val mcpSdk = "0.11.3"
+  val mcpSdk = "0.13.1"
   val scalaTest = "3.2.19"
 }
 
diff --git a/src/main/scala/com/tjclp/fastmcp/core/Types.scala b/src/main/scala/com/tjclp/fastmcp/core/Types.scala
index 5d89abd..ad41dd5 100644
--- a/src/main/scala/com/tjclp/fastmcp/core/Types.scala
+++ b/src/main/scala/com/tjclp/fastmcp/core/Types.scala
@@ -1,5 +1,6 @@
 package com.tjclp.fastmcp.core
 
+import io.modelcontextprotocol.json.McpJsonMapper
 import io.modelcontextprotocol.spec.McpSchema
 import io.modelcontextprotocol.spec.McpSchema.Tool
 import zio.json.*
@@ -45,8 +46,10 @@ object ToolDefinition:
         // Directly use McpSchema.JsonSchema
         baseToolBuilder.inputSchema(mcpSchema)
       case Right(stringSchema) =>
-        // Use string schema - MCP SDK will parse it
-        baseToolBuilder.inputSchema(stringSchema)
+        // Parse string schema to JsonSchema using McpJsonMapper
+        val jsonMapper = McpJsonMapper.createDefault()
+        val jsonSchema = jsonMapper.readValue(stringSchema, classOf[McpSchema.JsonSchema])
+        baseToolBuilder.inputSchema(jsonSchema)
     }
     toolBuilder.build()
 
diff --git a/src/main/scala/com/tjclp/fastmcp/server/FastMcpServer.scala b/src/main/scala/com/tjclp/fastmcp/server/FastMcpServer.scala
index a9f5b0f..9992a09 100644
--- a/src/main/scala/com/tjclp/fastmcp/server/FastMcpServer.scala
+++ b/src/main/scala/com/tjclp/fastmcp/server/FastMcpServer.scala
@@ -3,6 +3,7 @@ package server
 
 import com.tjclp.fastmcp.core.*
 import com.tjclp.fastmcp.server.manager.*
+import io.modelcontextprotocol.json.McpJsonMapper
 import io.modelcontextprotocol.server.McpAsyncServer
 import io.modelcontextprotocol.server.McpAsyncServerExchange
 import io.modelcontextprotocol.server.McpServer
@@ -160,7 +161,8 @@ class FastMcpServer(
     ZIO.scoped { // ⬅ drops the `Scope` requirement
       ZIO.acquireRelease(
         for {
-          provider <- ZIO.attempt(new StdioServerTransportProvider())
+          jsonMapper <- ZIO.attempt(McpJsonMapper.createDefault())
+          provider <- ZIO.attempt(new StdioServerTransportProvider(jsonMapper))
           _ <- ZIO.attempt(setupServer(provider))
           _ <- ZIO.attempt(
             JSystem.err.println(
diff --git a/src/test/scala/com/tjclp/fastmcp/TestFixtures.scala b/src/test/scala/com/tjclp/fastmcp/TestFixtures.scala
index 0e70fb8..b8c1f84 100644
--- a/src/test/scala/com/tjclp/fastmcp/TestFixtures.scala
+++ b/src/test/scala/com/tjclp/fastmcp/TestFixtures.scala
@@ -1,7 +1,7 @@
 package com.tjclp.fastmcp
 
-import com.fasterxml.jackson.core.`type`.TypeReference
 import com.tjclp.fastmcp.server.McpContext
+import io.modelcontextprotocol.json.TypeRef
 import io.modelcontextprotocol.server.McpAsyncServerExchange
 import io.modelcontextprotocol.spec.McpLoggableSession
 import io.modelcontextprotocol.spec.McpSchema
@@ -19,7 +19,7 @@ object TestFixtures {
     override def sendRequest[T](
         method: String,
         params: Object,
-        typeRef: TypeReference[T]
+        typeRef: TypeRef[T]
     ): Mono[T] = Mono.empty()
     override def sendNotification(method: String): Mono[Void] = Mono.empty()
     override def sendNotification(method: String, obj: Object): Mono[Void] = Mono.empty()
diff --git a/src/test/scala/com/tjclp/fastmcp/macros/ContextPropagationTest.scala b/src/test/scala/com/tjclp/fastmcp/macros/ContextPropagationTest.scala
index 8dca0cc..44076b3 100644
--- a/src/test/scala/com/tjclp/fastmcp/macros/ContextPropagationTest.scala
+++ b/src/test/scala/com/tjclp/fastmcp/macros/ContextPropagationTest.scala
@@ -1,7 +1,7 @@
 package com.tjclp.fastmcp
 package macros
 
-import com.fasterxml.jackson.core.`type`.TypeReference
+import io.modelcontextprotocol.json.TypeRef
 import io.modelcontextprotocol.server.McpAsyncServerExchange
 import io.modelcontextprotocol.spec.McpSchema
 import org.scalatest.funsuite.AnyFunSuite
@@ -130,7 +130,7 @@ class NoopLoggableSession extends io.modelcontextprotocol.spec.McpLoggableSessio
   override def sendRequest[T](
       method: String,
       params: Object,
-      typeRef: TypeReference[T]
+      typeRef: TypeRef[T]
   ): reactor.core.publisher.Mono[T] = reactor.core.publisher.Mono.empty()
 
   override def sendNotification(method: String): reactor.core.publisher.Mono[Void] =