AgentCore 0.16.0

Changed

• The opportunistic recovery for an invalid streamed tool call now retries with streaming instead of a non-streaming chat replay, so the retry's attempt events carry recovery_action="retry_streaming" instead of replay_non_streaming. Calls that match the previous empty-required-arguments condition keep the stream_empty_tool_arguments / stream_empty_args_replay reasons and the stream_empty_args_* response metadata; newly detected cases (invalid JSON or a non-object for tools without required fields) use stream_invalid_tool_call. When a native call is still invalid after the retry, the attempt finishes as accepted_degraded with reason invalid_tool_call and the call returns an error tool result (error_kind="invalid_arguments") instead of running the tool. Consumers asserting the old replay transport, its event names, or accepted for such attempts should update those assertions; set LoopConfig(tool_argument_validation="off") to keep only the legacy retry condition. AgentCore now depends on jsonschema>=4.20,<5.

Added

• Streaming can now be selected independently of token observers (LoopConfig.stream_transport, call_llm(stream=...)). Native tool calls are checked before execution according to the new LoopConfig.tool_argument_validation ("structural" by default, "strict" for full JSON Schema, "off"). Invalid streamed calls are retried once using streaming, and invalid native calls that remain return an explicit tool error instead of running. Blank arguments count as {}, text-mode calls and tool-side type coercion are unaffected, malformed tool schemas never fail a call, and native calls missing an id get a generated one instead of breaking history replay.