MCP client

[suzuki-safie]

Issue #, if available: https://github.com/aws-samples/bedrock-claude-chat/issues/816

Description of changes: This PR implements MCP client feature.

This supports remote MCP server through Streamable HTTP transport (2025-03-26) by requests based implementation. This also supports AWS IAM authentication (SIGv4A).

This PR doesn't include any configuration UI.

This PR is ~~not fully tested yet~~ tested against official TypeScript SDK and Lambda Web Adapter based deployment (with IAM auth).

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[statefb]

@suzuki-safie Thank you for your proposal. Could you explain the intended user experience? (If possible, pseudo-screenshots would help us understand better.)

[suzuki-safie]

@statefb Basic usecase:

1. A developer (who can modify and deploy bedrock-claude-chat) deploys an MCP server on the network. If the MCP server doesn't support Streamable HTTP transport, a proxy is required. In my particular case, I'm trying to host MCP servers on AWS Lambda with IAM authentication.
2. The developer registers the MCP server as an additional AgentTool in backend/app/agents/utils.py

   def get_available_tools() -> list[AgentTool | AgentToolBundle]:
      tools: list[AgentTool | AgentToolBundle] = []
      tools.append(internet_search_tool)
      tools.append(bedrock_agent_tool)
      tools.append(MCPAgentTool(
        name="mcp",
        description="MCP server",
        url="https://example.lambda-url.ap-northeast-1.on.aws/mcp",
        aws_sigv4a_service="lambda",
      ))
      return tools
   

3. Users (with CreatingBotAllowed permission) can create a bot with the mcp tool.
4. Users can chat with the bot using tools provided by MCP.

If remote MCP servers becomes popular, it would be nice to have a GUI to manage them like internet_search_tool.

[statefb]

@suzuki-safie Thank you for your response. This is a good start, but I have some feedback on making it align better:

• Accessibility for non-technical users: BrChat is designed to be accessible to users without deep technical knowledge. We should provide a proper configuration UI to make this feature truly accessible.

• Configuration approach: Ideally, users would configure MCP servers directly from the bot creation screen, similar to how VSCode extensions or Anthropic Claude Desktop work (json configuration). ~~The problem is almost use-cases need local MCP server, which is currently difficult to align the concept.~~ ~~As you mentioned on the issue, remote MCP server is not mature enough (growing rapidly though), so it might not be a good timing to implement, which means user needs to build and run their own server by wrapping API Gateway as you did~~ Some early adopter like Notion serves their own MCP server, which can be a good point to start.

[suzuki-safie]

Tested against https://github.com/modelcontextprotocol/typescript-sdk/blob/df8701937de07074d96438a59be7f6c344f9d359/src/examples/server/simpleStreamableHttp.ts

[statefb]

Thank you for your work on the MCP client implementation. Your technical approach looks solid and well-tested. One of the most prominent advantage of MCP would be "easy configurable experience" like q dev cli, Cline or VSCode.
For example, user can setup MCP easily on bot configuration screen by editing JSON like:

{
  "mcpServers": {
    "awslabs.aws-documentation-mcp-server": {
        "command": "uvx",
        "args": ["awslabs.aws-documentation-mcp-server@latest"],
        "env": {
          "FASTMCP_LOG_LEVEL": "ERROR"
        },
        "disabled": false,
        "autoApprove": []
    }
  }
}

source: https://awslabs.github.io/mcp/servers/aws-documentation-mcp-server/#installation

I'm trying to host MCP servers on AWS Lambda

The following can be a bridge between lambda and MCP client.
https://awslabs.github.io/mcp/servers/lambda-mcp-server/

As discussed, we prioritize UX for non-technical users in this project. We'd welcome further discussion on how we might develop a user-friendly configuration interface together. If you're interested in collaborating on the UI aspect, we're happy to discuss ideas and approaches.

[suzuki-safie]

Yesterday, Anthropic (and many MCP providers) announced remote MCP. https://x.com/AnthropicAI/status/1917972747000692919 These MCP servers have OAuth2-based authentication but this implementation does not work with them properly. (because of OAuth2, per-user MCP configuration is required.)