diff --git a/pyproject.toml b/pyproject.toml
index 61bec1d..6558805 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -20,7 +20,7 @@ dependencies = [
 # dependency so the systemd/CLI system-python path stays dependency-light and
 # never has to import the MCP SDK.
 [project.optional-dependencies]
-mcp = ["mcp>=1.9"]
+mcp = ["mcp>=1.9,<2"]
 
 # Explicit package discovery. Without this, setuptools' flat-layout
 # auto-discovery aborts because the repo root holds two top-level dirs
diff --git a/requirements.txt b/requirements.txt
index b15f941..0df4516 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -6,7 +6,7 @@ bandit>=1.7.0
 codespell>=2.2.0
 coverage>=7.4.0
 howlongtobeatpy>=1.0
-mcp>=1.9
+mcp>=1.9,<2
 mypy>=1.8.0
 pre-commit>=3.6.0
 pylint>=3.0.0