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Understand the AgentCore Runtime service contract - Amazon Bedrock AgentCore
Supported protocolsCompare supported protocolsReserved platform ports
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Understand the AgentCore Runtime service contract

The AgentCore Runtime service contract defines the standardized communication protocol that your agent application must implement to integrate with the Amazon Bedrock agent hosting infrastructure. This contract ensures seamless communication between your custom agent code and Amazon's managed hosting environment.

Topics

Supported protocols

The AgentCore Runtime service contract supports the following communication protocols:

  • HTTP : Direct REST API endpoints for traditional request/response patterns

  • MCP : Model Context Protocol for tools and agent servers

  • A2A : Agent-to-Agent protocol for multi-agent communication and discovery

  • AG-UI : Agent-to-User Interface protocol for interactive agent experiences with UI rendering

Compare supported protocols

Compare the HTTP, MCP, A2A, and AG-UI protocols to understand the differences and use cases.

Feature HTTP Protocol MCP Protocol A2A Protocol AG-UI Protocol

Default serving port

8080

8000

9000

8080

Default mount path

/invocations (HTTP), /ws (WebSocket)

/mcp

/ (root)

/invocations (SSE), /ws (WebSocket)

Message Format

REST JSON/SSE, WebSocket (text/binary)

JSON-RPC

JSON-RPC 2.0

Event streams (SSE/WebSocket)

Discovery

N/A

Tool listing

Agent Cards

N/A

Authentication

SigV4, OAuth 2.0; WebSocket supports SigV4 by headers and query params

SigV4, OAuth 2.0

SigV4, OAuth 2.0

SigV4, OAuth 2.0

Use Case

Direct API calls, real-time streaming

Tool servers

Agent-to-agent communication

Interactive UI experiences

You can configure the serving port and the POST path used by InvokeAgentRuntime. For configuration details and examples, see Configure your agent’s serving port and invocation path.

To access application-defined HTTP methods and paths or additional servers in a session, enable session endpoints with allowedPorts. For more information, see Connect to runtime sessions through a session endpoint.

Reserved platform ports

AgentCore Runtime reserves the following ports for platform use:

  • 1144

  • 1514

  • 1571

  • 2049

  • 4317–4318 (inclusive)

  • 8443

  • 48620

  • 48640

  • 53530–53532 (inclusive)

Choose other ports for your application servers. An allowedPorts entry cannot specify a reserved port or a range that contains any reserved port. For the other port validation rules, see Configure allowed ports.