diff --git a/agent/tools/retrieval.py b/agent/tools/retrieval.py
index f0823be69..bb44b124a 100644
--- a/agent/tools/retrieval.py
+++ b/agent/tools/retrieval.py
@@ -13,6 +13,8 @@
 #  See the License for the specific language governing permissions and
 #  limitations under the License.
 #
+from functools import partial
+import json
 import os
 import re
 from abc import ABC
@@ -131,7 +133,35 @@ class Retrieval(ToolBase, ABC):
                 if not doc_ids:
                     doc_ids = None
             elif self._param.meta_data_filter.get("method") == "manual":
-                doc_ids.extend(meta_filter(metas, self._param.meta_data_filter["manual"]))
+                filters=self._param.meta_data_filter["manual"]
+                for flt in filters:
+                    pat = re.compile(r"\{* *\{([a-zA-Z:0-9]+@[A-Za-z:0-9_.-]+|sys\.[a-z_]+)\} *\}*")
+                    s = flt["value"]
+                    out_parts = []
+                    last = 0
+
+                    for m in pat.finditer(s):
+                        out_parts.append(s[last:m.start()])
+                        key = m.group(1)
+                        v = self._canvas.get_variable_value(key)
+                        if v is None:
+                            rep = ""
+                        elif isinstance(v, partial):
+                            buf = []
+                            for chunk in v():
+                                buf.append(chunk)
+                            rep = "".join(buf)
+                        elif isinstance(v, str):
+                            rep = v
+                        else:
+                            rep = json.dumps(v, ensure_ascii=False)
+
+                        out_parts.append(rep)
+                        last = m.end()
+
+                    out_parts.append(s[last:])
+                    flt["value"] = "".join(out_parts)
+                doc_ids.extend(meta_filter(metas, filters))
                 if not doc_ids:
                     doc_ids = None