diff --git a/firebase-vertexai/src/main/kotlin/com/google/firebase/vertexai/common/shared/Types.kt b/firebase-vertexai/src/main/kotlin/com/google/firebase/vertexai/common/shared/Types.kt
index f6c1bc22b88..c34af862def 100644
--- a/firebase-vertexai/src/main/kotlin/com/google/firebase/vertexai/common/shared/Types.kt
+++ b/firebase-vertexai/src/main/kotlin/com/google/firebase/vertexai/common/shared/Types.kt
@@ -62,7 +62,7 @@ internal data class FunctionResponsePart(val functionResponse: FunctionResponse)
 @Serializable internal data class FunctionResponse(val name: String, val response: JsonObject)
 
 @Serializable
-internal data class FunctionCall(val name: String, val args: Map<String, String?>? = null)
+internal data class FunctionCall(val name: String, val args: Map<String, JsonElement?>? = null)
 
 @Serializable
 internal data class FileDataPart(@SerialName("file_data") val fileData: FileData) : Part
diff --git a/firebase-vertexai/src/main/kotlin/com/google/firebase/vertexai/internal/util/conversions.kt b/firebase-vertexai/src/main/kotlin/com/google/firebase/vertexai/internal/util/conversions.kt
index 5a86ee8de4a..ed846375d23 100644
--- a/firebase-vertexai/src/main/kotlin/com/google/firebase/vertexai/internal/util/conversions.kt
+++ b/firebase-vertexai/src/main/kotlin/com/google/firebase/vertexai/internal/util/conversions.kt
@@ -58,8 +58,8 @@ import com.google.firebase.vertexai.type.content
 import java.io.ByteArrayOutputStream
 import java.util.Calendar
 import kotlinx.serialization.json.Json
+import kotlinx.serialization.json.JsonNull
 import kotlinx.serialization.json.JsonObject
-import kotlinx.serialization.json.JsonPrimitive
 import org.json.JSONObject
 
 private const val BASE_64_FLAGS = Base64.NO_WRAP
@@ -97,10 +97,7 @@ internal fun Part.toInternal(): com.google.firebase.vertexai.common.shared.Part
 }
 
 internal fun FunctionCall.toInternal() =
-  com.google.firebase.vertexai.common.shared.FunctionCall(
-    name,
-    args.orEmpty().mapValues { it.value.toString() }
-  )
+  com.google.firebase.vertexai.common.shared.FunctionCall(name, args)
 
 internal fun FunctionResponse.toInternal() =
   com.google.firebase.vertexai.common.shared.FunctionResponse(name, response)
@@ -237,13 +234,7 @@ internal fun com.google.firebase.vertexai.common.shared.Part.toPublic(): Part {
 }
 
 internal fun com.google.firebase.vertexai.common.shared.FunctionCall.toPublic() =
-  FunctionCall(
-    name,
-    args.orEmpty().mapValues {
-      val argValue = it.value
-      if (argValue == null) JsonPrimitive(null) else Json.parseToJsonElement(argValue)
-    }
-  )
+  FunctionCall(name, args.orEmpty().mapValues { it.value ?: JsonNull })
 
 internal fun com.google.firebase.vertexai.common.shared.FunctionResponse.toPublic() =
   FunctionResponse(
diff --git a/firebase-vertexai/src/test/java/com/google/firebase/vertexai/UnarySnapshotTests.kt b/firebase-vertexai/src/test/java/com/google/firebase/vertexai/UnarySnapshotTests.kt
index 50113660208..a71d8e16c08 100644
--- a/firebase-vertexai/src/test/java/com/google/firebase/vertexai/UnarySnapshotTests.kt
+++ b/firebase-vertexai/src/test/java/com/google/firebase/vertexai/UnarySnapshotTests.kt
@@ -45,6 +45,8 @@ import io.ktor.http.HttpStatusCode
 import kotlin.time.Duration.Companion.seconds
 import kotlinx.coroutines.withTimeout
 import kotlinx.serialization.json.JsonPrimitive
+import kotlinx.serialization.json.jsonObject
+import kotlinx.serialization.json.jsonPrimitive
 import org.json.JSONArray
 import org.junit.Test
 
@@ -372,6 +374,27 @@ internal class UnarySnapshotTests {
       }
     }
 
+  @Test
+  fun `function call with complex json literal parses correctly`() =
+    goldenUnaryFile("unary-success-function-call-complex-json-literal.json") {
+      withTimeout(testTimeout) {
+        val response = model.generateContent("prompt")
+        val content = response.candidates.shouldNotBeNullOrEmpty().first().content
+        val callPart =
+          content.let {
+            it.shouldNotBeNull()
+            it.parts.shouldNotBeEmpty()
+            it.parts.first().shouldBeInstanceOf<FunctionCallPart>()
+          }
+
+        callPart.functionCall.args["current"] shouldBe JsonPrimitive(true)
+        callPart.functionCall.args["testObject"]!!
+          .jsonObject["testProperty"]!!
+          .jsonPrimitive
+          .content shouldBe "string property"
+      }
+    }
+
   @Test
   fun `function call contains no arguments`() =
     goldenUnaryFile("unary-success-function-call-no-arguments.json") {
diff --git a/firebase-vertexai/src/test/java/com/google/firebase/vertexai/common/UnarySnapshotTests.kt b/firebase-vertexai/src/test/java/com/google/firebase/vertexai/common/UnarySnapshotTests.kt
index b08eb104248..6749a31e952 100644
--- a/firebase-vertexai/src/test/java/com/google/firebase/vertexai/common/UnarySnapshotTests.kt
+++ b/firebase-vertexai/src/test/java/com/google/firebase/vertexai/common/UnarySnapshotTests.kt
@@ -36,6 +36,7 @@ import io.ktor.http.HttpStatusCode
 import kotlin.time.Duration.Companion.seconds
 import kotlinx.coroutines.withTimeout
 import kotlinx.serialization.Serializable
+import kotlinx.serialization.json.JsonPrimitive
 import org.junit.Test
 
 @Serializable internal data class MountainColors(val name: String, val colors: List<String>)
@@ -330,7 +331,7 @@ internal class UnarySnapshotTests {
           }
 
         callPart.functionCall.args shouldNotBe null
-        callPart.functionCall.args?.get("current") shouldBe "true"
+        callPart.functionCall.args?.get("current") shouldBe JsonPrimitive(true)
       }
     }