Switch field name for tool

Author: jonathan-buttner

server/src/main/java/org/elasticsearch/inference/UnifiedCompletionRequest.java

@@ -37,7 +37,7 @@ public record UnifiedCompletionRequest(
     @Nullable Stop stop,
     @Nullable Float temperature,
     @Nullable ToolChoice toolChoice,
-    @Nullable List<Tool> tool,
+    @Nullable List<Tool> tools,
     @Nullable Float topP,
     @Nullable String user
 ) implements Writeable {
@@ -114,7 +114,7 @@ public void writeTo(StreamOutput out) throws IOException {
         out.writeOptionalNamedWriteable(stop);
         out.writeOptionalFloat(temperature);
         out.writeOptionalNamedWriteable(toolChoice);
-        out.writeOptionalCollection(tool);
+        out.writeOptionalCollection(tools);
         out.writeOptionalFloat(topP);
         out.writeOptionalString(user);
     }