bedrock-kb-retrieval-mcp-server: Kiro CLI unable to use Knowledge Base in us-west-2 region

[nemec]

Describe the bug

using the MCP with a knowledge base in us-west-2 throws an error that the KB doesn't exist, while it works in us-east-1

Expected Behavior

I'd expect it to work in both regions

Current Behavior

using the MCP with a knowledge base in us-west-2 throws an error that the KB doesn't exist, while it works in us-east-1

Reproduction Steps

I've configured my MCP like the following:

{
  "mcpServers" : {
    "awslabs.bedrock-kb-retrieval-mcp-server": {
      "command": "uvx",
      "args": ["awslabs.bedrock-kb-retrieval-mcp-server@latest"],
      "env": {
        "AWS_PROFILE": "<myrole>",
        "AWS_REGION": "us-west-2",
        "FASTMCP_LOG_LEVEL": "ERROR",
        "BEDROCK_KB_RERANKING_ENABLED": "false"
      },
      "disabled": false,
      "autoApprove": []
    }
  }
}

Then I start kiro-cli and prompt it with:

use the MCP `awslabs.bedrock-kb-retrieval-mcp-server` with the knowledge base ID `<myid>` to figure out the architecture of abc service

This knowledge base exists in us-west-2

Kiro executes the following:

Running tool QueryKnowledgeBases with the param (from mcp server: awslabs.bedrock-kb-retrieval-mcp-server)
 ⋮  {
 ⋮    "knowledge_base_id": "<myid>",
 ⋮    "query": "abc service architecture",
 ⋮    "number_of_results": 10
 ⋮  }

The result is

> The knowledge base ID <myid> doesn't exist or isn't accessible. Let me try listing available knowledge bases to see what's available [...]

When I ask Kiro for the error message, it states the following:

> The error message is:

An error occurred (ResourceNotFoundException) when calling the Retrieve operation: Knowledge Base with id <myid> does not exist

My role has the AmazonBedrockFullAccess managed policy, so it shouldn't be a permissions issue. I'm also able to see the results when fetching the KB using the same profile as in my MCP settings:

aws bedrock-agent get-knowledge-base --knowledge-base-id <myid> --region us-west-2

I created a second knowledge base in us-east-1 and tried the same thing:

use the MCP `awslabs.bedrock-kb-retrieval-mcp-server` with the knowledge base ID `<otherid>` to figure out the architecture of abc service

Even without changing the AWS_REGION set in my MCP settings environment variable from us-west-2 to us-east-1, this tool execution now succeeds:

Running tool QueryKnowledgeBases with the param (from mcp server: awslabs.bedrock-kb-retrieval-mcp-server)
 ⋮  {
 ⋮    "knowledge_base_id": "<otherid>",
 ⋮    "number_of_results": 10,
 ⋮    "query": "abc service architecture design components"
 ⋮  }

Possible Solution

No response

Additional Information/Context

No response

OS

Mac

Server

bedrock-kb-retrieval-mcp-server

Server Version

No response

Region experiencing the issue

us-west-2

Other information

No response

Service quota

• I have reviewed the service quotas for this construct