deps(a2a): address interface changes and bump min version (#515)

Co-authored-by: jer <jerebill@amazon.com>

Author: jer96

pyproject.toml

@@ -90,7 +90,7 @@ writer = [
 ]
 
 a2a = [
-    "a2a-sdk[sql]>=0.2.11,<1.0.0",
+    "a2a-sdk[sql]>=0.2.16,<1.0.0",
     "uvicorn>=0.34.2,<1.0.0",
     "httpx>=0.28.1,<1.0.0",
     "fastapi>=0.115.12,<1.0.0",
@@ -136,7 +136,7 @@ all = [
     "opentelemetry-exporter-otlp-proto-http>=1.30.0,<2.0.0",
 
     # a2a
-    "a2a-sdk[sql]>=0.2.11,<1.0.0",
+    "a2a-sdk[sql]>=0.2.16,<1.0.0",
     "uvicorn>=0.34.2,<1.0.0",
     "httpx>=0.28.1,<1.0.0",
     "fastapi>=0.115.12,<1.0.0",

src/strands/multiagent/a2a/server.py

@@ -83,8 +83,8 @@ def public_agent_card(self) -> AgentCard:
             url=self.http_url,
             version=self.version,
             skills=self.agent_skills,
-            defaultInputModes=["text"],
-            defaultOutputModes=["text"],
+            default_input_modes=["text"],
+            default_output_modes=["text"],
             capabilities=self.capabilities,
         )