| name | aws-serverless |
| description | Build and deploy serverless applications with AWS Lambda, SAM, API Gateway, EventBridge, Step Functions, and event-driven architectures |
| argument-hint | [what are you building?] |
| allowed-tools | Bash(sam *), Bash(aws *), Bash(cdk *), Bash(docker *), Read, Glob, Grep, Edit, Write |
AWS Serverless Plugin
Overview
Build and deploy serverless applications with AWS Lambda, SAM, API Gateway, and the complete AWS serverless ecosystem. This skill provides access to comprehensive serverless development tools through the AWS Serverless MCP Server, enabling you to build production-ready serverless applications with best practices built-in.
Use SAM CLI for project initialization and deployment, Lambda Web Adapter for web applications, or Event Source Mappings for event-driven architectures. The platform handles infrastructure provisioning, scaling, and monitoring automatically.
Key capabilities:
- SAM CLI Integration: Initialize, build, deploy, and test serverless applications
- Web Application Deployment: Deploy full-stack applications with Lambda Web Adapter
- Event Source Mappings: Configure Lambda triggers for DynamoDB, Kinesis, SQS, Kafka
- Schema Management: Type-safe EventBridge integration with schema registry
- Observability: CloudWatch logs, metrics, and X-Ray tracing
- Performance Optimization: Right-sizing, cost optimization, and troubleshooting
Workflow Guidance
Refer to these supporting files for detailed guidance on specific workflows:
| File | When to Use |
|---|
| getting-started.md | Decision tree: what are you building? Routes to the right template, runtime, and guide |
| sam-project-setup.md | SAM project initialization, template selection, development workflow, and testing |
| cdk-project-setup.md | CDK as an alternative to SAM: constructs, patterns, testing, and deployment |
| web-app-deployment.md | Full-stack deployment patterns with Lambda Web Adapter, authentication, and response streaming |
| event-sources.md | Lambda event sources: S3, SNS, DynamoDB, Kinesis, SQS, Kafka, MQ, and DocumentDB |
| event-driven-architecture.md | EventBridge rules, event design, choreography vs orchestration, Pipes, schema registry |
| orchestration-and-workflows.md | Multi-step workflows with Lambda Durable Functions or Step Functions |
| optimization.md | Performance tuning, cost optimization, Lambda SnapStart, Managed Instances, and Powertools |
| observability.md | Structured logging, distributed tracing, custom metrics, alarms, dashboards, and Logs Insights |
| troubleshooting.md | Symptom-based diagnosis and resolution for common issues |
Best Practices
Project Setup
- Do: Use
sam_init or cdk init with an appropriate template for your use case
- Do: Set global defaults for timeout, memory, runtime, and tracing (
Globals in SAM, construct props in CDK)
- Do: Use AWS Lambda Powertools for structured logging, tracing, metrics (EMF), idempotency, and batch processing — available for Python, TypeScript, Java, and .NET
- Don't: Copy-paste templates from the internet without understanding the resource configuration
- Don't: Use the same memory and timeout values for all functions regardless of workload
Security
- Do: Follow least-privilege IAM policies scoped to specific resources and actions
- Do: Use
secure_esm_* tools to generate correct IAM policies for event source mappings
- Do: Store secrets in AWS Secrets Manager or SSM Parameter Store, never in environment variables
- Do: Use VPC endpoints instead of NAT Gateways for AWS service access when possible
- Do: Enable Amazon GuardDuty Lambda Protection to monitor function network activity for threats (cryptocurrency mining, data exfiltration, C2 callbacks)
- Don't: Use wildcard (
*) resource ARNs or actions in IAM policies
- Don't: Hardcode credentials or secrets in application code or templates
- Don't: Store user data or sensitive information in module-level variables — execution environments can be reused across different callers
Idempotency
- Do: Write idempotent function code — Lambda delivers events at least once, so duplicate invocations must be safe
- Do: Use the AWS Lambda Powertools Idempotency utility (backed by DynamoDB) for critical operations
- Do: Validate and deduplicate events at the start of the handler before performing side effects
- Don't: Assume an event will only ever be processed once
For topic-specific best practices, see the dedicated guide files in the Workflow Guidance table above.
Lambda Limits Quick Reference
Limits that developers commonly hit:
| Resource | Limit |
|---|
| Function timeout | 900 seconds (15 minutes) |
| Memory | 128 MB – 10,240 MB |
| 1 vCPU equivalent | 1,769 MB memory |
| Synchronous payload (request + response) | 6 MB each |
| Async invocation payload | 1 MB |
| Streamed response | 200 MB |
| Deployment package (.zip, uncompressed) | 250 MB |
| Deployment package (.zip upload, compressed) | 50 MB |
| Container image | 10 GB |
| Layers per function | 5 |
| Environment variables (aggregate) | 4 KB |
/tmp ephemeral storage | 512 MB – 10,240 MB |
| Account concurrent executions (default) | 1,000 (requestable increase) |
| Burst scaling rate | 1,000 new executions per 10 seconds |
Check Service Quotas for your account limits: aws lambda get-account-settings
Troubleshooting Quick Reference
| Error | Cause | Solution |
|---|
Build Failed | Missing dependencies | Run sam_build with use_container: true |
Stack is in ROLLBACK_COMPLETE | Previous deploy failed | Delete stack with aws cloudformation delete-stack, redeploy |
IteratorAge increasing | Stream consumer falling behind | Increase ParallelizationFactor and BatchSize. Use esm_optimize |
| EventBridge events silently dropped | No DLQ, retries exhausted | Add RetryPolicy + DeadLetterConfig to rule target |
| Step Functions failing silently | No retry on Task state | Add Retry with Lambda.ServiceException, Lambda.AWSLambdaException |
| Durable Function not resuming | Missing IAM permissions | Add lambda:CheckpointDurableExecution and lambda:GetDurableExecutionState |
For detailed troubleshooting, see troubleshooting.md.
Configuration
Authentication Setup
This skill requires AWS credentials configured on the host machine:
- Install AWS CLI: Follow the AWS CLI installation guide
- Configure credentials: Run
aws configure or set up named profiles in ~/.aws/credentials
- Set environment variables (if not using the default profile):
AWS_PROFILE - Named profile to useAWS_REGION - Target AWS region
- Verify access: Run
aws sts get-caller-identity to confirm credentials are valid
SAM CLI Setup
- Install SAM CLI: Follow the SAM CLI installation guide
- Install Docker Desktop: Required for
sam_local_invoke and container-based builds
- Verify: Run
sam --version and docker --version
MCP Server Configuration
The MCP server is configured in .mcp.json with the following flags:
--allow-write: Enables write operations (project creation, deployments)--allow-sensitive-data-access: Enables access to Lambda logs and API Gateway logs
SAM Template Validation Hook
This plugin includes a PostToolUse hook that runs sam validate automatically after any edit to template.yaml or template.yml. If validation fails, the error is returned as a system message so you can fix it immediately. The hook requires SAM CLI to be installed and silently skips if it is not available. Users can disable it via /hooks.
Version policy: .mcp.json uses awslabs.aws-serverless-mcp-server@latest. This is intentional — the package is pre-1.0 (currently 0.1.x) and under active development, so pinning would miss bug fixes and new tool capabilities. If you need a stable, reproducible setup, pin to a specific version:
"args": ["awslabs.aws-serverless-mcp-server@0.1.17", "--allow-write", "--allow-sensitive-data-access"]
Check for new versions with uvx pip index versions awslabs.aws-serverless-mcp-server.
