Tools, MCP & Gateway

AgentCore Gateway is the universal tool bridge: it translates any backend — Lambda functions, OpenAPI services, Smithy services, API Gateway endpoints, or MCP servers — into a single MCP interface that agents consume without writing custom adapters or managing backend credentials.

The platform also provides:

  • BaseMCPServer — a base class for building domain MCP servers with transport handling, tool registration, $defs flattening, and observability built in
  • Built-in tools — Code Interpreter and Browser, both Gateway-mediated with no local SDK client
  • Artifact Store — a Lambda-backed MCP tool set implementing the claim-check pattern for large outputs that would otherwise exceed Step Functions payload limits

In This Section

Page What It Covers
Gateway Protocol translation, the five target types (Lambda, MCP Server, OpenAPI, Smithy, API Gateway), two auth layers (inbound SigV4/JWT, outbound IAM/OAuth2), gateway-targets.yaml format, GatewayClient usage
MCP Servers BaseMCPServer usage and $defs flattening, Redis cache layer (cache_get/cache_set), execution-mode provider routing (resolve_provider), naming conventions
Built-in Tools Code Interpreter and Browser providers — Gateway-mediated, dynamically discovered, no local lifecycle management
Artifacts Claim-check pattern, the four MCP tools (create_artifact, get_artifact, list_artifacts, poll_artifact), two-tier S3/KMS security model, signed URL strategies, SQS notifications

Key Design Principle

Agents never connect directly to tool backends. Every tool call — whether to a Lambda function, an MCP server, or a built-in AWS service — goes through Gateway. This means:

  • Credentials stay in one place (resolved by Gateway), not scattered across agent code
  • Policy enforcement (Cedar) happens centrally at Gateway before any backend is reached
  • Agents mix local tools and remote Gateway tools in a single flat tool list
  • Backend infrastructure can change without modifying agent code

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