fix(agents): consider tool's customName in tools from callable (#1883)

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Fix the big "@tool(customName = ...) is ignored when using
ToolSet.asTools() / ToolRegistryBuilder.tools(ToolSet)" and add a test.

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KG-1. Otherwise, delete it. -->
closes #1881

Author: aozherelyeva

agents/agents-tools/src/jvmCommonMain/kotlin/ai/koog/agents/core/tools/reflect/ToolFromCallableExtensions.kt

@@ -65,7 +65,8 @@ public fun <T : Any> KClass<out T>.asTools(
     return this.functions.filter { m ->
         m.getPreferredToolAnnotation() != null
     }.map {
-        it.asTool(thisRef = thisRef)
+        val customName = it.getPreferredToolAnnotation()?.customName?.ifEmpty { null }
+        it.asTool(thisRef = thisRef, name = customName)
     }.apply {
         require(isNotEmpty()) { "No tools found in ${this@asTools}" }
     }

agents/agents-tools/src/jvmTest/kotlin/ai/koog/agents/core/tools/reflect/ToolSetAsToolsTest.kt

@@ -1,5 +1,6 @@
 package ai.koog.agents.core.tools.reflect
 
+import ai.koog.agents.core.tools.ToolRegistry
 import ai.koog.agents.core.tools.annotations.InternalAgentToolsApi
 import ai.koog.agents.core.tools.annotations.LLMDescription
 import ai.koog.agents.core.tools.annotations.Tool
@@ -103,6 +104,22 @@ class ComplexToolsImpl : ToolSet {
     ): String = "${person.name} is ${person.age} years old"
 }
 
+class SearchToolA : ToolSet {
+    @Tool(customName = "tool_a_search")
+    @LLMDescription("Searches source A")
+    fun execute(
+        @LLMDescription("Query") query: String
+    ): String = "result A: $query"
+}
+
+class SearchToolB : ToolSet {
+    @Tool(customName = "tool_b_search")
+    @LLMDescription("Searches source B")
+    fun execute(
+        @LLMDescription("Query") query: String
+    ): String = "result B: $query"
+}
+
 @OptIn(InternalAgentToolsApi::class)
 class ToolSetAsToolsTest {
     private val serializer = KotlinxSerializer()
@@ -241,4 +258,24 @@ class ToolSetAsToolsTest {
             "Format tool should return formatted string"
         )
     }
+
+    @Test
+    @OptIn(InternalAgentToolsApi::class)
+    fun testCustomToolNamesArePreservedForToolSets() {
+        val toolA = SearchToolA()
+        val toolB = SearchToolB()
+
+        val toolANames = toolA.asTools().map { it.descriptor.name }
+        val toolBNames = toolB.asTools().map { it.descriptor.name }
+
+        assertEquals(listOf("tool_a_search"), toolANames)
+        assertEquals(listOf("tool_b_search"), toolBNames)
+
+        val registry = ToolRegistry {
+            tools(toolA)
+            tools(toolB)
+        }
+
+        assertEquals(listOf("tool_a_search", "tool_b_search"), registry.tools.map { it.name }.sorted())
+    }
 }