Ensures that the type field for each AnthropicToolSchema is serialized when we construct the request body.

prompt/prompt-executor/prompt-executor-clients/prompt-executor-anthropic-client/src/commonMain/kotlin/ai/koog/prompt/executor/clients/anthropic/DataModel.kt

@@ -249,20 +249,23 @@ public data class AnthropicTool(
  * Represents a schema definition for an Anthropic tool utilized in LLM clients. This data class
  * defines the structure expected for tools, including the type of schema, properties, and required fields.
  *
- * This API is internal and should not be used outside of its intended scope, as it might be subject
+ * This API is internal and should not be used outside its intended scope, as it might be subject
  * to changes or removal without notice.
  *
- * @property type The type of the schema, defaulting to "object".
  * @property properties A JSON object representing the properties within this schema.
  * @property required A list of property names that are mandatory within this schema.
  */
 @InternalLLMClientApi
 @Serializable
 public data class AnthropicToolSchema(
-    val type: String = "object",
     val properties: JsonObject,
     val required: List<String>
-)
+) {
+    /**
+     * The type of the schema. Always returns "object" for Anthropic tool schemas.
+     */
+    val type: String = "object"
+}
 
 /**
  * Represents the response structure from an Anthropic API call.

prompt/prompt-executor/prompt-executor-clients/prompt-executor-bedrock-client/src/jvmTest/kotlin/ai/koog/prompt/executor/clients/bedrock/modelfamilies/anthropic/BedrockAnthropicClaudeSerializationTest.kt

@@ -394,4 +394,41 @@ class BedrockAnthropicClaudeSerializationTest {
         val content = BedrockAnthropicClaudeSerialization.parseAnthropicStreamChunk(chunkJson)
         assertEquals("", content)
     }
+
+    @Test
+    fun `createAnthropicRequest with tools serializes type field correctly`() {
+        val tools = listOf(
+            ToolDescriptor(
+                name = toolName,
+                description = toolDescription,
+                requiredParameters = listOf(
+                    ToolParameterDescriptor("city", "The city name", ToolParameterType.String)
+                ),
+                optionalParameters = listOf(
+                    ToolParameterDescriptor("units", "Temperature units", ToolParameterType.String)
+                )
+            )
+        )
+        val prompt = Prompt.build("test", params = LLMParams(toolChoice = LLMParams.ToolChoice.Auto)) {
+            user(userMessageQuestion)
+        }
+        val request = BedrockAnthropicClaudeSerialization.createAnthropicRequest(prompt, model, tools)
+        assertNotNull(request)
+        assertNotNull(request.tools)
+        assertEquals(1, request.tools?.size)
+        val tool = request.tools?.get(0)
+        assertNotNull(tool)
+        assertEquals(toolName, tool.name)
+        assertEquals(toolDescription, tool.description)
+        val schema = tool.inputSchema
+        assertNotNull(schema)
+
+        // Verify that the type field is always "object" and gets serialized
+        assertEquals("object", schema.type)
+
+        assertEquals(listOf("city"), schema.required)
+        val properties = schema.properties.jsonObject
+        assertNotNull(properties["city"])
+        assertNotNull(properties["units"])
+    }
 }