diff --git a/src/fgai/graylog_mcp.py b/src/fgai/graylog_mcp.py
index d5b37ec..f1e7799 100644
--- a/src/fgai/graylog_mcp.py
+++ b/src/fgai/graylog_mcp.py
@@ -20,9 +20,9 @@ class GraylogMcpClient:
             payload["id"] = 1
         if params is not None:
             payload["params"] = params
-        credentials = base64.b64encode(f"{self.token}:token".encode("utf-8")).decode("ascii")
+        authorization = self._authorization_header()
         headers = {
-            "Authorization": f"Basic {credentials}",
+            "Authorization": authorization,
             "Content-Type": "application/json",
             "Accept": "application/json, text/event-stream",
         }
@@ -49,6 +49,20 @@ class GraylogMcpClient:
             raise RuntimeError(f"mcp_error: {response_data['error']}")
         return response_data
 
+    def _authorization_header(self) -> str:
+        """Accept a raw token or the Basic/Base64 form commonly copied from MCP clients."""
+        value = self.token.strip()
+        if value.lower().startswith("basic "):
+            return value
+        try:
+            decoded = base64.b64decode(value, validate=True).decode("utf-8")
+        except (ValueError, UnicodeDecodeError):
+            decoded = ""
+        if decoded.endswith(":token"):
+            return f"Basic {value}"
+        credentials = base64.b64encode(f"{value}:token".encode("utf-8")).decode("ascii")
+        return f"Basic {credentials}"
+
     def probe(self) -> dict[str, object]:
         initialized = self._call(
             "initialize",
diff --git a/tests/test_graylog_mcp.py b/tests/test_graylog_mcp.py
index caeb949..47097ce 100644
--- a/tests/test_graylog_mcp.py
+++ b/tests/test_graylog_mcp.py
@@ -21,6 +21,12 @@ class _Response:
 
 
 class GraylogMcpTests(unittest.TestCase):
+    def test_accepts_raw_or_copied_basic_credentials(self):
+        raw = GraylogMcpClient("http://graylog/api/mcp", "raw-token")._authorization_header()
+        encoded = raw.removeprefix("Basic ")
+        self.assertEqual(GraylogMcpClient("http://graylog/api/mcp", encoded)._authorization_header(), raw)
+        self.assertEqual(GraylogMcpClient("http://graylog/api/mcp", raw)._authorization_header(), raw)
+
     def test_probe_initializes_and_lists_tools(self):
         responses = iter([
             _Response({"result": {"serverInfo": {"version": "7.1.6"}}}),