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AWS bedrock-agentcore documentation change

Service: bedrock-agentcore · 2026-05-31 · Documentation low

File: bedrock-agentcore/latest/devguide/release-notes.md

Summary

Added release notes for new AgentCore features: CDK construct stability, MCP sessions, response streaming, elicitation pass-through, sampling messages, and progress/logging notifications.

Security assessment

The changes document new functionality enhancements (session management, streaming, interactive workflows) without addressing security vulnerabilities or describing security-specific features. No evidence of patching vulnerabilities or security-focused content exists.

Diff

diff --git a/bedrock-agentcore/latest/devguide/release-notes.md b/bedrock-agentcore/latest/devguide/release-notes.md
index afc26da89..d0d786299 100644
--- a//bedrock-agentcore/latest/devguide/release-notes.md
+++ b//bedrock-agentcore/latest/devguide/release-notes.md
@@ -14,0 +15,24 @@ We recommend subscribing to the RSS feed so updates to these notes are delivered
+### AWS CDK: AgentCore Constructs Graduate to Stable
+
+The aws-bedrockagentcore L2 constructs have graduated from alpha to stable in aws-cdk-lib. Customers can now define AgentCore resources (runtime, memory, gateway, identity, and more) using CDK with full backward-compatibility guarantees, no separate -alpha package required. The Policy submodule remains in alpha. See [CDK release notes](https://github.com/aws/aws-cdk/releases/tag/v2.255.0).
+
+### Gateway: MCP Sessions
+
+AgentCore gateway can now maintain stateful sessions with MCP clients, allowing them to receive a unique Mcp-Session-Id on initialize and track session state (including downstream MCP target sessions, and pending elicitation or sampling request interactions). Sessions are scoped per authenticated user with configurable timeouts (default 1 hour, up to 8 hours). MCP Sessions serves as the foundation for all interactive MCP features below. See [Use MCP sessions with your AgentCore gateway](https://docs.aws.amazon.com/bedrock-agentcore/latest/devguide/gateway-sessions.html).
+
+### Gateway: Response Streaming
+
+AgentCore Gateway now supports Server-Sent-Events (SSE), delivering multiple JSON-RPC messages on a single connection. Previously, the gateway buffered the entire target response and returned only the final result. Now, events from MCP server targets are delivered as they’re produced, enabling the real-time capabilities below.
+
+### Gateway: Elicitation Pass-Through
+
+MCP servers targets on AgentCore Gateway can now request input from end users mid-tool-execution. The gateway proxies these elicitation requests to the client and routes responses back to the correct downstream server. Supported modes: Form mode — Server sends a structured form (e.g., "Confirm you want to proceed with this refund?"), user responds, server continues. URL mode — Server directs the user to a URL (e.g., OAuth consent page), then completes processing once the user finishes. This enables interactive, human-in-the-loop workflows through a managed gateway — no custom infrastructure required. See [Use elicitation with your AgentCore gateway](https://docs.aws.amazon.com/bedrock-agentcore/latest/devguide/gateway-mcp-elicitation.html).
+
+### Gateway: Sampling Messages
+
+MCP servers can now request LLM completions from the client during tool execution. The gateway transparently relays these server-initiated requests, enabling patterns where tools augment their behavior with model reasoning mid-flight. See [Use sampling with your AgentCore gateway](https://docs.aws.amazon.com/bedrock-agentcore/latest/devguide/gateway-mcp-sampling.html).
+
+### Gateway: Progress Notifications & Logging Notifications
+
+Clients now receive real-time progress updates and structured log messages from tools as they execute. Previously, the gateway returned only the final result. Now, long-running operations can report incremental progress and emit diagnostic logs that stream directly to the caller. See documentation for [progress notifications](https://docs.aws.amazon.com/bedrock-agentcore/latest/devguide/gateway-mcp-progress.html) and [logging messages](https://docs.aws.amazon.com/bedrock-agentcore/latest/devguide/gateway-mcp-logging.html).
+