aws-sar-mcp

FastMCP server exposing the AWS Service Authorization Reference — query IAM actions, find destructive operations, and search across all AWS services.

What This Is

The AWS Service Authorization Reference is AWS's own database of every IAM action for every service. This server fetches it and exposes it as MCP tools — so any Claude client can query it directly.

No AWS credentials required. The SAR is a public API.

Tools

Example Queries

Once connected, ask Claude:

"What S3 actions can delete things?"
→ sar_delete_actions("s3")
→ s3:DeleteBucket, s3:DeleteObject, s3:DeleteObjectVersion...

"What IAM actions involve encryption?"
→ sar_search("encrypt", services=["kms", "s3", "secretsmanager"])
→ kms:Encrypt, kms:GenerateDataKey, s3:PutEncryptionConfiguration...

"How many write actions does EC2 have vs ECS?"
→ sar_compare("ec2", "ecs")
→ EC2: 312 total (89 Write), ECS: 87 total (31 Write)

"What can I do with SQS at the Read level?"
→ sar_actions_by_level("sqs", "Read")
→ sqs:GetQueueAttributes, sqs:GetQueueUrl, sqs:ReceiveMessage...

Architecture

Claude Desktop / Claude Code / Custom Agent
              │
              │ MCP (stdio or http)
              ▼
     aws-sar-mcp (FastMCP server)
              │
              ├── sar_lookup()
              ├── sar_delete_actions()
              ├── sar_actions_by_level()     ──► SAR API (public)
              ├── sar_search()               https://servicereference
              ├── sar_compare()                  .us-east-1.amazonaws.com/v1
              └── sar_list_services()
                        │
                    TTL Cache (1hr)
                    No re-fetch while warm

Quick Start

Install

git clone https://github.com/TanishkaMarrott/aws-sar-mcp.git
cd aws-sar-mcp
pip install -r requirements.txt

Connect to Claude Code

claude mcp add aws-sar -- fastmcp run /path/to/aws-sar-mcp/server.py

Connect to Claude Desktop

Add to claude_desktop_config.json:

{
  "mcpServers": {
    "aws-sar": {
      "command": "fastmcp",
      "args": ["run", "/path/to/aws-sar-mcp/server.py"]
    }
  }
}

Run standalone

fastmcp run server.py

Run Tests

pytest tests/
# Tests hit the real SAR API — no mocking, no credentials needed

Why This Is Useful

For security engineers:

• Quickly find all destructive actions before writing deny policies
• Compare permission sets between similar services
• Search for risky patterns (e.g. sar_search("PassRole"))

For AI agents:

• Agents that enforce IAM policies need to know what actions exist
• Combine with dual-agent-memory — Resource Finder uses SAR to validate cleanup targets

For developers:

• Understand what a service can do before requesting permissions
• Write least-privilege policies without reading AWS docs manually

Project Structure

aws-sar-mcp/
├── server.py          # FastMCP server — 6 tools
├── sar/
│   └── client.py      # SAR API client with TTL caching
└── tests/
    └── test_sar.py    # Integration tests (real API)

Author

Built by Tanishka Marrott — AI Agent Systems Engineer