chore: Update SDK documentation (#2265)

Co-authored-by: marvin-context-protocol[bot] <225465937+marvin-context-protocol[bot]@users.noreply.github.com>

docs/python-sdk/fastmcp-server-auth-providers-debug.mdx

@@ -0,0 +1,70 @@
+---
+title: debug
+sidebarTitle: debug
+---
+
+# `fastmcp.server.auth.providers.debug`
+
+
+Debug token verifier for testing and special cases.
+
+This module provides a flexible token verifier that delegates validation
+to a custom callable. Useful for testing, development, or scenarios where
+standard verification isn't possible (like opaque tokens without introspection).
+
+Example:
+    ```python
+    from fastmcp import FastMCP
+    from fastmcp.server.auth.providers.debug import DebugTokenVerifier
+
+    # Accept all tokens (default - useful for testing)
+    auth = DebugTokenVerifier()
+
+    # Custom sync validation logic
+    auth = DebugTokenVerifier(validate=lambda token: token.startswith("valid-"))
+
+    # Custom async validation logic
+    async def check_cache(token: str) -> bool:
+        return await redis.exists(f"token:{token}")
+
+    auth = DebugTokenVerifier(validate=check_cache)
+
+    mcp = FastMCP("My Server", auth=auth)
+    ```
+
+
+## Classes
+
+### `DebugTokenVerifier` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/auth/providers/debug.py#L40" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
+
+
+Token verifier with custom validation logic.
+
+This verifier delegates token validation to a user-provided callable.
+By default, it accepts all non-empty tokens (useful for testing).
+
+Use cases:
+- Testing: Accept any token without real verification
+- Development: Custom validation logic for prototyping
+- Opaque tokens: When you have tokens with no introspection endpoint
+
+WARNING: This bypasses standard security checks. Only use in controlled
+environments or when you understand the security implications.
+
+
+**Methods:**
+
+#### `verify_token` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/auth/providers/debug.py#L77" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
+
+```python
+verify_token(self, token: str) -> AccessToken | None
+```
+
+Verify token using custom validation logic.
+
+**Args:**
+- `token`: The token string to validate
+
+**Returns:**
+- AccessToken if validation succeeds, None otherwise
+