diff --git a/src/fastmcp/client/auth.py b/src/fastmcp/client/auth.py
index bd63419a2..6165fdfd8 100644
--- a/src/fastmcp/client/auth.py
+++ b/src/fastmcp/client/auth.py
@@ -1,7 +1,6 @@
 from __future__ import annotations
 
 import asyncio
-import datetime
 import json
 import webbrowser
 from pathlib import Path
@@ -20,10 +19,9 @@ from mcp.shared.auth import (
     OAuthMetadata as _MCPServerOAuthMetadata,
 )
 from mcp.shared.auth import (
-    OAuthToken as _MCPOAuthToken,
+    OAuthToken as OAuthToken,
 )
-from pydantic import AnyHttpUrl, ValidationError, model_validator
-from typing_extensions import Self
+from pydantic import AnyHttpUrl, ValidationError
 
 from fastmcp.client.oauth_callback import (
     create_oauth_callback_server,
@@ -37,19 +35,8 @@ __all__ = ["OAuth"]
 logger = get_logger(__name__)
 
 
-class OAuthToken(_MCPOAuthToken):
-    """
-    OAuth token that stores expiration as a datetime object
-    """
-
-    expires_at: datetime.datetime | None = None
-
-    @model_validator(mode="after")
-    def set_expires_at(self) -> Self:
-        if self.expires_in is not None and self.expires_at is None:
-            now = datetime.datetime.now(datetime.timezone.utc)
-            self.expires_at = now + datetime.timedelta(seconds=self.expires_in)
-        return self
+def default_cache_dir() -> Path:
+    return fastmcp_global_settings.home / "oauth-mcp-client-cache"
 
 
 # Flexible OAuth models for real-world compatibility
@@ -140,9 +127,7 @@ class FileTokenStorage(TokenStorage):
     def __init__(self, server_url: str, cache_dir: Path | None = None):
         """Initialize storage for a specific server URL."""
         self.server_url = server_url
-        self.cache_dir = (
-            cache_dir or fastmcp_global_settings.home / "oauth-mcp-client-cache"
-        )
+        self.cache_dir = cache_dir or default_cache_dir()
         self.cache_dir.mkdir(exist_ok=True, parents=True)
 
     @staticmethod
@@ -172,10 +157,10 @@ class FileTokenStorage(TokenStorage):
 
         try:
             tokens = OAuthToken.model_validate_json(path.read_text())
-            now = datetime.datetime.now(datetime.timezone.utc)
-            if tokens.expires_at is not None and tokens.expires_at <= now:
-                logger.debug(f"Token expired for {self.get_base_url(self.server_url)}")
-                return None
+            # now = datetime.datetime.now(datetime.timezone.utc)
+            # if tokens.expires_at is not None and tokens.expires_at <= now:
+            #     logger.debug(f"Token expired for {self.get_base_url(self.server_url)}")
+            #     return None
             return tokens
         except (FileNotFoundError, json.JSONDecodeError, ValidationError) as e:
             logger.debug(
@@ -183,10 +168,8 @@ class FileTokenStorage(TokenStorage):
             )
             return None
 
-    async def set_tokens(self, tokens: _MCPOAuthToken) -> None:
+    async def set_tokens(self, tokens: OAuthToken) -> None:
         """Save tokens to file storage."""
-        # Convert to custom model with expiration datetime
-        tokens = OAuthToken.model_validate(tokens.model_dump())
         path = self._get_file_path("tokens")
         path.write_text(tokens.model_dump_json(indent=2))
         logger.debug(f"Saved tokens for {self.get_base_url(self.server_url)}")
@@ -195,7 +178,24 @@ class FileTokenStorage(TokenStorage):
         """Load client information from file storage."""
         path = self._get_file_path("client_info")
         try:
-            return OAuthClientInformationFull.model_validate_json(path.read_text())
+            client_info = OAuthClientInformationFull.model_validate_json(
+                path.read_text()
+            )
+            # Check if we have corresponding valid tokens
+            # If no tokens exist, the OAuth flow was incomplete and we should
+            # force a fresh client registration
+            tokens = await self.get_tokens()
+            if tokens is None:
+                logger.debug(
+                    f"No tokens found for client info at {self.get_base_url(self.server_url)}. "
+                    "OAuth flow may have been incomplete. Clearing client info to force fresh registration."
+                )
+                # Clear the incomplete client info
+                client_info_path = self._get_file_path("client_info")
+                client_info_path.unlink(missing_ok=True)
+                return None
+
+            return client_info
         except (FileNotFoundError, json.JSONDecodeError, ValidationError) as e:
             logger.debug(
                 f"Could not load client info for {self.get_base_url(self.server_url)}: {e}"
@@ -208,7 +208,7 @@ class FileTokenStorage(TokenStorage):
         path.write_text(client_info.model_dump_json(indent=2))
         logger.debug(f"Saved client info for {self.get_base_url(self.server_url)}")
 
-    def clear_cache(self) -> None:
+    def clear(self) -> None:
         """Clear all cached data for this server."""
         file_types: list[Literal["client_info", "tokens"]] = ["client_info", "tokens"]
         for file_type in file_types:
@@ -219,7 +219,7 @@ class FileTokenStorage(TokenStorage):
     @classmethod
     def clear_all(cls, cache_dir: Path | None = None) -> None:
         """Clear all cached data for all servers."""
-        cache_dir = cache_dir or fastmcp_global_settings.home / "oauth-mcp-client-cache"
+        cache_dir = cache_dir or default_cache_dir()
         if not cache_dir.exists():
             return