diff --git a/src/mcp/server/__init__.py b/src/mcp/server/__init__.py
index aaf581435..ca7ef90ab 100644
--- a/src/mcp/server/__init__.py
+++ b/src/mcp/server/__init__.py
@@ -111,7 +111,7 @@ def __init__(self, name: str):
     def create_initialization_options(
         self,
         notification_options: NotificationOptions | None = None,
-        experimental_capabilities: dict[str, dict[str, Any]] | None = None,
+        experimental_capabilities: dict[str, object] | None = None,
     ) -> InitializationOptions:
         """Create initialization options from this server instance."""
 
@@ -139,7 +139,7 @@ def pkg_version(package: str) -> str:
     def get_capabilities(
         self,
         notification_options: NotificationOptions,
-        experimental_capabilities: dict[str, dict[str, Any]],
+        experimental_capabilities: dict[str, object],
     ) -> types.ServerCapabilities:
         """Convert existing handlers to a ServerCapabilities object."""
         prompts_capability = None
diff --git a/src/mcp/types.py b/src/mcp/types.py
index a2b897403..b8bb90f4b 100644
--- a/src/mcp/types.py
+++ b/src/mcp/types.py
@@ -201,7 +201,7 @@ class SamplingCapability(BaseModel):
 class ClientCapabilities(BaseModel):
     """Capabilities a client may support."""
 
-    experimental: dict[str, dict[str, Any]] | None = None
+    experimental: dict[str, object] | None = None
     """Experimental, non-standard capabilities that the client supports."""
     sampling: SamplingCapability | None = None
     """Present if the client supports sampling from an LLM."""
@@ -245,7 +245,7 @@ class LoggingCapability(BaseModel):
 class ServerCapabilities(BaseModel):
     """Capabilities that a server may support."""
 
-    experimental: dict[str, dict[str, Any]] | None = None
+    experimental: dict[str, object] | None = None
     """Experimental, non-standard capabilities that the server supports."""
     logging: LoggingCapability | None = None
     """Present if the server supports sending log messages to the client."""