diff --git a/src/youtube_extension/services/agents/antigravity_backend.py b/src/youtube_extension/services/agents/antigravity_backend.py
index f2e245a6f..84ae445c0 100644
--- a/src/youtube_extension/services/agents/antigravity_backend.py
+++ b/src/youtube_extension/services/agents/antigravity_backend.py
@@ -20,7 +20,7 @@
 
 
 ANTIGRAVITY_AGENT = "antigravity-preview-05-2026"
-_MCP_NAME = re.compile(r"^[a-z0-9_-]+$")
+_MCP_NAME = re.compile(r"^[a-z0-9]+$")
 
 
 class AntigravityConfigurationError(ValueError):
@@ -51,7 +51,7 @@ class AntigravityMCPServer:
     def validate(self, read_only_tools: frozenset[str]) -> None:
         if not _MCP_NAME.fullmatch(self.name):
             raise AntigravityConfigurationError(
-                "MCP server name must match ^[a-z0-9_-]+$"
+                "MCP server name must contain lowercase ASCII letters and digits only"
             )
         parsed = urlparse(self.url)
         if parsed.scheme != "https" or not parsed.netloc:
@@ -171,12 +171,17 @@ def build_payload(
             "video_uri",
             "audio",
             "audio_file",
+            "image",
+            "images",
+            "image_bytes",
+            "image_file",
+            "image_uri",
             "document",
         }
         present = sorted(forbidden.intersection(context))
         if present:
             raise AntigravityConfigurationError(
-                "Antigravity accepts normalized text/image context, not direct media: "
+                "This adapter accepts normalized text context, not direct media: "
                 + ", ".join(present)
             )
 
diff --git a/tests/unit/test_antigravity_backend.py b/tests/unit/test_antigravity_backend.py
index 2286bde84..60bb3dee0 100644
--- a/tests/unit/test_antigravity_backend.py
+++ b/tests/unit/test_antigravity_backend.py
@@ -107,17 +107,18 @@ async def test_live_transport_requires_two_explicit_gates() -> None:
         await backend.execute("do work")
 
 
+@pytest.mark.parametrize("media_key", ["video_uri", "image_uri"])
 @pytest.mark.asyncio
-async def test_direct_media_is_rejected_before_transport() -> None:
+async def test_direct_media_is_rejected_before_transport(media_key: str) -> None:
     transport = FakeTransport()
     backend = AntigravityBackend(config(), transport)
 
     with pytest.raises(AntigravityConfigurationError, match="direct media"):
-        await backend.execute("analyze", {"video_uri": "gs://bucket/video.mp4"})
+        await backend.execute("analyze", {media_key: "gs://bucket/media"})
     assert transport.payloads == []
 
 
-@pytest.mark.parametrize("name", ["EventRelay", "event relay", "eventrelay!"])
+@pytest.mark.parametrize("name", ["EventRelay", "event relay", "eventrelay!", "event-relay", "event_relay"])
 def test_mcp_name_must_match_provider_contract(name: str) -> None:
     invalid = config(
         mcp_servers=(