diff --git a/snappy_pipeline/workflows/somatic_msi_calling/model.py b/snappy_pipeline/workflows/somatic_msi_calling/model.py
new file mode 100644
index 000000000..53fab3a94
--- /dev/null
+++ b/snappy_pipeline/workflows/somatic_msi_calling/model.py
@@ -0,0 +1,20 @@
+import enum
+from typing import Annotated
+
+from pydantic import Field
+
+from models import SnappyStepModel, EnumField
+
+
+class Tool(enum.Enum):
+    mantis = "mantis"
+
+
+class SomaticMsiCalling(SnappyStepModel):
+    path_ngs_mapping: str
+
+    tools: Annotated[list[Tool], EnumField(Tool, [Tool.mantis])]
+
+    loci_bed: Annotated[
+        str, Field(examples=["/fast/groups/cubi/projects/biotools/Mantis/appData/hg19/loci.bed"])
+    ]