diff --git a/src/skillspector/mcp_server.py b/src/skillspector/mcp_server.py
index e377d972..a27845a3 100644
--- a/src/skillspector/mcp_server.py
+++ b/src/skillspector/mcp_server.py
@@ -176,6 +176,11 @@ def build_server(name: str = "skillspector", *, allow_local_targets: bool = Fals
     try:
         from mcp.server.fastmcp import FastMCP
     except ModuleNotFoundError as exc:
+        if exc.name != "mcp":
+            raise ModuleNotFoundError(
+                "The installed 'mcp' package is incompatible with the SkillSpector "
+                "MCP server. Reinstall with: pip install 'skillspector[mcp]'"
+            ) from exc
         raise ModuleNotFoundError(
             "The MCP server requires the optional 'mcp' dependency. "
             "Install it with: pip install 'skillspector[mcp]'"
diff --git a/tests/unit/test_mcp_server.py b/tests/unit/test_mcp_server.py
index 3e7243c3..bccc9f4f 100644
--- a/tests/unit/test_mcp_server.py
+++ b/tests/unit/test_mcp_server.py
@@ -441,6 +441,23 @@ async def test_build_server_disables_local_targets_by_default(
     assert graph_ainvoke.await_count == 0
 
 
+def test_build_server_reports_incompatible_mcp(monkeypatch: pytest.MonkeyPatch) -> None:
+    """An installed package without FastMCP must not be reported as missing."""
+    import builtins
+
+    original_import = builtins.__import__
+
+    def import_without_fastmcp(name: str, *args: object, **kwargs: object) -> object:
+        if name == "mcp.server.fastmcp":
+            raise ModuleNotFoundError("No module named 'mcp.server.fastmcp'", name=name)
+        return original_import(name, *args, **kwargs)
+
+    monkeypatch.setattr(builtins, "__import__", import_without_fastmcp)
+
+    with pytest.raises(ModuleNotFoundError, match="installed 'mcp' package is incompatible"):
+        mcp_server.build_server()
+
+
 async def test_mcp_stdio_initialize_registers_scan_skill() -> None:
     """The real stdio CLI must initialize and expose the scan_skill tool."""
     pytest.importorskip("mcp")
diff --git a/uv.lock b/uv.lock
index c4f6b6a8..b79cedaa 100644
--- a/uv.lock
+++ b/uv.lock
@@ -1,5 +1,5 @@
 version = 1
-revision = 2
+revision = 3
 requires-python = ">=3.12, <3.15"
 resolution-markers = [
     "python_full_version >= '3.14' and sys_platform == 'win32'",