AWS has published a full reference architecture for MCP Apps, the extension that lets a Model Context Protocol server ship a user interface alongside its tools. In Build interactive MCP Apps using Amazon Bedrock AgentCore, Dantis Stephen and Babs Khalidson walk through a unicorn rental demo where the AI host renders the available unicorns as interactive cards, served from widget HTML the MCP server returns as a resource. “Everything you just saw is served by a single MCP server running on Amazon Bedrock AgentCore runtime, fronted by an AgentCore Gateway.” The argument is portability: “Because MCP Apps is a host-agnostic standard, the app delivers the same rich experience across AI hosts that support the Apps extension.”
There are no numbers to discount, which is normal for an AWS solutions post, and the claims are architectural. The pattern is a thin MCP protocol adapter on the AgentCore runtime that delegates business logic to a Lambda function and serves self-contained widget HTML, with AWS WAF in front of the gateway for IP allowlisting, managed threat rules, and rate limiting, CloudWatch for error rates and latency, and Bedrock Guardrails at the trust boundary. The advice is sound and unremarkable, and the part worth keeping is the shape: the MCP layer stays thin and the services stay portable, so the host can be ChatGPT or Claude and the backend does not care. That is the same argument MCP itself makes, extended one layer up to the interface.
The catalog carries Bedrock as a strong provider, and the AgentCore surface the post is built on is not in it. The Amazon Bedrock provider page lists 8 API pages, all of them the foundation-model surface: the Amazon Bedrock Agent API and the Amazon Bedrock Agent Runtime API are the nearest relatives to what AgentCore runs, and the Amazon Bedrock Converse API is what the unicorn assistant would be talking to. The agentic access profile maps 12 operations, 6 of them acting. AgentCore, the runtime and gateway the post is about, has no API page under the record, which means the catalog is a product behind AWS on this one.
The Kin Score is 55.8, strong band, the highest of the three providers profiled today. Access clarity carries it at 81.6 and discoverability at 68.5, contract quality at 63.6. Developer ergonomics is 46.4, operational transparency 39.5, contract governance 25.0. The Agent Readiness score is 23.0, agent-aware, and the unlit list is the finding. The MCP server dimension is unlit. So is auth clarity, because the catalog record describes SigV4 signing in prose and no contract declares it as a scheme. So is every identity dimension: delegated identity, protected resource metadata, dynamic client registration. AWS has written the reference architecture for hosting an MCP server that carries its own interface, and the Bedrock record cannot show an agent a single MCP server or an authentication scheme it could use to reach one. The post builds the house. The record has not yet published the address.