diff --git a/requirements.txt b/requirements.txt
--- a/requirements.txt
+++ b/requirements.txt
@@ -3,3 +3,4 @@
 # dependency lines, see https://pip.readthedocs.org/en/1.1/requirements.html
 click
 elasticsearch>=7.0.0,<8.0.0
+typing-extensions
diff --git a/swh/search/elasticsearch.py b/swh/search/elasticsearch.py
--- a/swh/search/elasticsearch.py
+++ b/swh/search/elasticsearch.py
@@ -12,7 +12,7 @@
 from swh.indexer import codemeta
 from swh.model import model
 from swh.model.identifiers import origin_identifier
-from swh.search.interface import PagedResult
+from swh.search.interface import MinimalOriginDict, OriginDict, PagedResult
 from swh.search.metrics import send_metric, timed
 
 
@@ -125,7 +125,7 @@
         self._backend.indices.refresh(index=self.origin_index)
 
     @timed
-    def origin_update(self, documents: Iterable[Dict]) -> None:
+    def origin_update(self, documents: Iterable[OriginDict]) -> None:
         documents = map(_sanitize_origin, documents)
         documents_with_sha1 = (
             (origin_identifier(document), document) for document in documents
@@ -191,7 +191,7 @@
         visit_types: Optional[List[str]] = None,
         page_token: Optional[str] = None,
         limit: int = 50,
-    ) -> PagedResult[Dict[str, Any]]:
+    ) -> PagedResult[MinimalOriginDict]:
         query_clauses: List[Dict[str, Any]] = []
 
         if url_pattern:
diff --git a/swh/search/in_memory.py b/swh/search/in_memory.py
--- a/swh/search/in_memory.py
+++ b/swh/search/in_memory.py
@@ -9,7 +9,7 @@
 from typing import Any, Dict, Iterable, Iterator, List, Optional
 
 from swh.model.identifiers import origin_identifier
-from swh.search.interface import PagedResult
+from swh.search.interface import MinimalOriginDict, OriginDict, PagedResult
 
 _words_regexp = re.compile(r"\w+")
 
@@ -53,14 +53,16 @@
 
     _url_splitter = re.compile(r"\W")
 
-    def origin_update(self, documents: Iterable[Dict]) -> None:
-        for document in documents:
-            document = document.copy()
+    def origin_update(self, documents: Iterable[OriginDict]) -> None:
+        for source_document in documents:
+            document: Dict[str, Any] = dict(source_document)
             id_ = origin_identifier(document)
             if "url" in document:
-                document["_url_tokens"] = set(self._url_splitter.split(document["url"]))
+                document["_url_tokens"] = set(
+                    self._url_splitter.split(source_document["url"])
+                )
             if "visit_types" in document:
-                document["visit_types"] = set(document["visit_types"])
+                document["visit_types"] = set(source_document["visit_types"])
                 if "visit_types" in self._origins[id_]:
                     document["visit_types"].update(self._origins[id_]["visit_types"])
             self._origins[id_].update(document)
@@ -77,7 +79,7 @@
         visit_types: Optional[List[str]] = None,
         page_token: Optional[str] = None,
         limit: int = 50,
-    ) -> PagedResult[Dict[str, Any]]:
+    ) -> PagedResult[MinimalOriginDict]:
         hits: Iterator[Dict[str, Any]] = (
             self._origins[id_] for id_ in self._origin_ids
         )
diff --git a/swh/search/interface.py b/swh/search/interface.py
--- a/swh/search/interface.py
+++ b/swh/search/interface.py
@@ -3,7 +3,9 @@
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
-from typing import Any, Dict, Iterable, List, Optional, TypeVar
+from typing import Iterable, List, Optional, TypeVar
+
+from typing_extensions import TypedDict
 
 from swh.core.api import remote_api_endpoint
 from swh.core.api.classes import PagedResult as CorePagedResult
@@ -12,6 +14,19 @@
 PagedResult = CorePagedResult[TResult, str]
 
 
+class MinimalOriginDict(TypedDict):
+    """Mandatory keys of an :cls:`OriginDict`"""
+
+    url: str
+
+
+class OriginDict(MinimalOriginDict, total=False):
+    """Argument passed to :meth:`SearchInterface.origin_update`."""
+
+    visit_types: List[str]
+    has_visits: bool
+
+
 class SearchInterface:
     @remote_api_endpoint("check")
     def check(self):
@@ -29,7 +44,7 @@
         ...
 
     @remote_api_endpoint("origin/update")
-    def origin_update(self, documents: Iterable[Dict]) -> None:
+    def origin_update(self, documents: Iterable[OriginDict]) -> None:
         """Persist documents to the search backend.
 
         """
@@ -45,7 +60,7 @@
         visit_types: Optional[List[str]] = None,
         page_token: Optional[str] = None,
         limit: int = 50,
-    ) -> PagedResult[Dict[str, Any]]:
+    ) -> PagedResult[MinimalOriginDict]:
         """Searches for origins matching the `url_pattern`.
 
         Args: