AWS Infrastructure MCP Server

A local FastMCP server (Python 3.12+, stdio transport) that exposes AWS diagnostic tools for serverless applications directly to IDE AI agents. It connects Cursor, VS Code Copilot, or Claude Code to CloudWatch, Lambda, DynamoDB, IAM, and Bedrock through the Model Context Protocol.

Architecture & Design Choices

Transport & Stack

Authentication

Uses boto3's default credential chain with no custom auth logic. The chain checks, in order: environment variables (AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY) → ~/.aws/credentials → ~/.aws/config → instance metadata. Set AWS_PROFILE to target a specific named profile.

Tool Surface

15 tools across 4 modules:

CloudWatch & Lambda — Service Diagnostics (tools/cloudwatch.py, tools/lambda_ops.py)

DynamoDB — Data Health (tools/dynamodb.py)

IAM — Security Governance (tools/iam.py)

validate_least_privilege checks:

1. Wildcard permissions — statements with "Action": "*" or "Resource": "*"

2. Dangerous managed policies — AdministratorAccess or PowerUserAccess attached

3. Unscoped data access — S3 or DynamoDB read/write actions without specific resource ARNs

Bedrock — AI Root-Cause Analysis (tools/bedrock.py)

Accepts raw text (logs, stack traces, metric summaries). Returns a validated Pydantic object:

class IncidentAnalysis(BaseModel):
    severity: Literal["LOW", "MEDIUM", "HIGH", "CRITICAL"]
    root_cause_summary: str
    affected_components: list[str]
    recommended_fix: str

The model_id parameter accepts any Bedrock-available model (for example: meta.llama3-2-3b).

Security Boundary

• All tools are read-only except invoke_lambda (synchronous invocation only).

• No tool creates, updates, or deletes Lambda functions, DynamoDB items, IAM policies, or any other AWS resource.

• A global credential scrubber (utils/scrubber.py) redacts AWS access key IDs, secret access keys, and session tokens from all tool outputs before data reaches the LLM context. Applied to log messages, invocation responses, and error outputs.

Project Structure

mcpserver/
├── app.py                 # FastMCP instance (single shared object)
├── server.py              # Entry point — imports tool modules, runs stdio
├── tools/
│   ├── __init__.py
│   ├── cloudwatch.py      # get_lambda_logs, get_lambda_errors, get_lambda_metrics
│   ├── lambda_ops.py      # list_lambdas, invoke_lambda
│   ├── dynamodb.py        # list_tables, describe_table, query_table, scan_table, get_table_metrics
│   ├── iam.py             # list_roles, get_role_policy, validate_least_privilege, list_lambda_roles
│   └── bedrock.py         # analyze_incident + IncidentAnalysis schema
├── utils/
│   ├── __init__.py
│   └── scrubber.py        # Credential redaction regex patterns
├── tests/
│   ├── test_scrubber.py
│   ├── test_cloudwatch.py
│   ├── test_lambda_ops.py
│   ├── test_dynamodb.py
│   ├── test_iam.py
│   └── test_bedrock.py
├── pyproject.toml
└── uv.lock

Installation & Local Setup

Prerequisites:

• Python 3.12+

• uv package manager

• AWS CLI configured (~/.aws/credentials or environment variables)

# Clone and install dependencies
cd mcpserver
uv sync

# Run the server locally (stdio)
uv run python server.py

IDE Configuration

VS Code / Cursor

Create .vscode/mcp.json in the project root:

{
  "servers": {
    "aws-infra-mcp": {
      "type": "stdio",
      "command": "uv",
      "args": ["--directory", "/absolute/path/to/mcpserver", "run", "server.py"]
    }
  }
}

Replace /absolute/path/to/mcpserver with the actual path to this directory. On Windows, use forward slashes (C:/Users/.../mcpserver).

Claude Desktop

Add to claude_desktop_config.json:

{
  "mcpServers": {
    "aws-infra-mcp": {
      "command": "uv",
      "args": ["--directory", "/absolute/path/to/mcpserver", "run", "server.py"]
    }
  }
}

Testing Strategy

Tests use a single-seam design: each @mcp.tool() function is tested at its public boundary with boto3 mocked beneath it using unittest.mock.patch. Tests verify the tool's transformation logic — log filtering, hard cap enforcement, credential scrubbing, Pydantic validation — without requiring live AWS credentials or making network calls.

57 unit tests across 6 test files:

# Run the full suite
uv run pytest

# Run a single cluster's tests
uv run pytest tests/test_iam.py -v