From f256b5b9b1e4795137b184f406cee6c07287e323 Mon Sep 17 00:00:00 2001
From: jupiter <1404785625@qq.com>
Date: Wed, 8 Jul 2026 01:51:58 +0800
Subject: [PATCH] fix(mcp): preserve blob resource contents

---
 .../proxy/_experimental/mcp_server/server.py  |  3 ++-
 .../mcp_server/test_mcp_server.py             | 25 ++++++++++++++++++-
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/litellm/proxy/_experimental/mcp_server/server.py b/litellm/proxy/_experimental/mcp_server/server.py
index e3812522ded..f42a506fc12 100644
--- a/litellm/proxy/_experimental/mcp_server/server.py
+++ b/litellm/proxy/_experimental/mcp_server/server.py
@@ -5,6 +5,7 @@ LiteLLM MCP Server Routes
 # pyright: reportInvalidTypeForm=false, reportArgumentType=false, reportOptionalCall=false
 
 import asyncio
+import base64
 import contextlib
 import contextvars
 import hashlib
@@ -385,7 +386,7 @@ if MCP_AVAILABLE:
             elif isinstance(content, BlobResourceContents):
                 normalized.append(
                     ReadResourceContents(
-                        content=content.blob,
+                        content=base64.b64decode(content.blob),
                         mime_type=content.mimeType,
                         meta=meta,
                     )
diff --git a/tests/test_litellm/proxy/_experimental/mcp_server/test_mcp_server.py b/tests/test_litellm/proxy/_experimental/mcp_server/test_mcp_server.py
index 1f44160aef4..99331976b88 100644
--- a/tests/test_litellm/proxy/_experimental/mcp_server/test_mcp_server.py
+++ b/tests/test_litellm/proxy/_experimental/mcp_server/test_mcp_server.py
@@ -756,11 +756,34 @@ def test_normalize_resource_contents_blob_with_metadata():
     result = _normalize_resource_contents(contents)
 
     assert len(result) == 1
-    assert result[0].content == "aGVsbG8="
+    assert result[0].content == b"hello"
     assert result[0].mime_type == "image/png"
     assert result[0].meta == meta
 
 
+def test_normalize_resource_contents_decodes_blob_content_to_bytes():
+    try:
+        from litellm.proxy._experimental.mcp_server.server import (
+            _normalize_resource_contents,
+        )
+    except ImportError:
+        pytest.skip("MCP server not available")
+
+    contents = [
+        BlobResourceContents(
+            uri="https://example.com/archive.tar.gz",
+            blob="H4sIAAAAAAACAw==",
+            mimeType="application/gzip",
+        )
+    ]
+
+    result = _normalize_resource_contents(contents)
+
+    assert len(result) == 1
+    assert result[0].content == b"\x1f\x8b\x08\x00\x00\x00\x00\x00\x02\x03"
+    assert result[0].mime_type == "application/gzip"
+
+
 def test_normalize_resource_contents_preserves_empty_metadata():
     """Test that empty dict meta is preserved (truthiness bug fix)."""
     try: