Identity-based policy examples for AWS MCP Server

The following examples show how to use IAM policies with the MCP condition context keys to control access through AWS MCP Server. Each example shows the policy statement to include within your IAM policy document.

Deny all actions through any AWS managed MCP server

The following SCP or IAM policy denies all actions when the request originates from any AWS managed MCP server. Use this to completely block MCP server access across an organization or for specific principals.

{
    "Sid": "DenyAllActionsViaMCP",
    "Effect": "Deny",
    "Action": "*",
    "Resource": "*",
    "Condition": {
        "Bool": {
            "aws:ViaAWSMCPService": "true"
        }
    }
}

Deny destructive actions through AWS MCP Server

The following policy allows read operations but denies destructive actions when the request comes through AWS MCP Server. This lets AI agents inspect resources without being able to delete them.

[
    {
        "Sid": "AllowS3ReadOperations",
        "Effect": "Allow",
        "Action": [
            "s3:GetObject",
            "s3:ListBucket"
        ],
        "Resource": "*"
    },
    {
        "Sid": "DenyDeleteWhenAccessedViaMCP",
        "Effect": "Deny",
        "Action": [
            "s3:DeleteObject",
            "s3:DeleteBucket"
        ],
        "Resource": "*",
        "Condition": {
            "StringEquals": {
                "aws:CalledViaAWSMCP": "aws-mcp.amazonaws.com"
            }
        }
    }
]

Restrict actions to a specific MCP server

The following policy denies all actions when the request comes specifically through AWS MCP Server, while allowing requests from other AWS managed MCP servers or direct API calls.

{
    "Sid": "DenyActionsViaAWSMCPServer",
    "Effect": "Deny",
    "Action": "*",
    "Resource": "*",
    "Condition": {
        "StringEquals": {
            "aws:CalledViaAWSMCP": "aws-mcp.amazonaws.com"
        }
    }
}