AWS MCP Gateway

AWS MCP Gateway is a security-focused Model Context Protocol server that lets ChatGPT read selected AWS account data through explicit, read-only tools.

It runs as a Cloudflare Worker, authenticates requests, validates every tool input, signs allowed AWS API calls, and returns normalized results without exposing generic AWS API access.

What is this?

This project is a self-hosted MCP gateway for connecting ChatGPT to AWS account data in a controlled way.

Instead of giving ChatGPT broad AWS credentials, shell access, or a generic AWS API proxy, the gateway exposes a small set of audited MCP tools. Each tool has a fixed purpose, validated input, bounded output, and read-only AWS permissions.

Every public tool is manifest-backed: a ToolManifest in src/mcp/tools/definitions/ is the source of truth for registration, ChatGPT descriptors, AWS capability metadata, and cost-control limits. A central policy gate runs before handler execution and fails closed when a tool pack is disabled, cost-control metadata is missing, or request limits are exceeded.

ChatGPT Connector
  -> OAuth / bearer authentication
  -> Cloudflare Worker /mcp endpoint
  -> Manifest-backed tool registry
  -> Policy gate (packs, cost-control, capabilities)
  -> Typed read-only handlers
  -> Signed read-only AWS API requests
  -> Normalized AWS cost, inventory, alarm, and log data

The registry defines 38 public tools. Default deployments expose 21 through tool packs (core, cost, inventory, observability, database). Three aggregate overview tools are opt-in via the aggregates pack. Five security tools (SSM inventory, S3 posture, SES configuration, SNS topic status, EventBridge/Scheduler status) are opt-in via the security pack. Nine application profile tools are opt-in via the application-ops pack. See tool exposure and docs/aws-capability-matrix.md.

Related MCP server: aws-safe-mcp

Current status

The gateway is currently designed for:

• remote MCP usage over HTTPS;

• ChatGPT custom app connector integration;

• OAuth-based ChatGPT connector authentication;

• local bearer mode development;

• read-only AWS cost, EC2, Lambda, S3, CloudWatch, and CloudWatch Logs inspection.

Production deployments should still run the verification and acceptance checks documented in docs/chatgpt-connector-production-acceptance.md.

Features

• Remote MCP endpoint at /mcp.

• ChatGPT-compatible OAuth connector flow.

• Explicit read-only AWS tools only.

• No generic AWS CLI or arbitrary AWS API proxy.

• Least-privilege IAM policy template.

• Region allowlist and input validation.

• Cloudflare KV caching for AWS-backed tool responses.

• OAuth request rate limiting with a Durable Object.

• Offline unit tests with a fetch guard against accidental network calls.

• Contract checks for MCP tool discovery and ChatGPT connector compatibility.

Available MCP tools

The registry defines 38 public read-only tools. Default deployments expose 21 via tool packs. Opt-in packs add security posture tools (security), aggregate overviews (aggregates), and KV-backed application profile workflows (application-ops).

See tool exposure for pack mappings and configuration examples. Full per-tool contracts: docs/mcp-tools.md. Platform architecture: docs/specs/secure-tool-platform.md.

When to use it

Use this gateway when you want ChatGPT to answer questions such as:

• “How much did my AWS account spend this month?”

• “Which services are driving my AWS bill?”

• “What EC2 instances are running in my allowed regions?”

• “Are there any CloudWatch alarms in ALARM state?”

• “What Lambda functions are deployed in my allowed regions?”

• “What S3 buckets exist in my account?”

• “Which CloudWatch log groups are defined in us-east-1?”

The project is useful for personal AWS account inspection, lightweight cloud operations, cost visibility, and controlled ChatGPT-based observability workflows.

When not to use it

Do not use this project as-is if you need:

• AWS write or management operations;

• provisioning, remediation, or infrastructure mutation;

• arbitrary AWS API access;

• a generic AWS CLI over MCP;

• multi-tenant SaaS isolation;

• a dashboard, database, or long-running backend service.

Management tools may be added later only behind stricter security boundaries. See docs/post-mvp-boundaries.md.

Requirements

• Node.js >=22

• pnpm 11.8.0

• Cloudflare account with Workers enabled

• AWS account with a dedicated read-only IAM user

• Wrangler authentication or a scoped Cloudflare API token

• Auth0 or another OIDC-compatible provider for production ChatGPT OAuth setup

Quick start: local development

Install dependencies:

pnpm install

Create local runtime secrets:

cp .dev.vars.example .dev.vars

Edit .dev.vars and fill:

AWS_ACCESS_KEY_ID=
AWS_SECRET_ACCESS_KEY=
AWS_REGION=us-east-1
AWS_ALLOWED_REGIONS=us-east-1,sa-east-1
AUTH_MODE=local-bearer
MCP_AUTH_TOKEN=

Minimal local loop (fast iteration during development):

pnpm run typecheck
pnpm test
pnpm run test:integrity

Full pre-PR / pre-deploy validation (same gate as docs/deployment.md):

pnpm run repo:safety
pnpm run output:guardrail
pnpm run verify:connector-contract
pnpm run typecheck
pnpm test
pnpm run test:integrity

verify:connector-contract runs typecheck, unit tests, and test-integrity checks; the last three commands are listed explicitly to match CI and deployment docs. Gitleaks secret scanning runs separately on every PR via .github/workflows/secret-scan.yml.

Start the local Worker:

pnpm dev

The local MCP endpoint is available at:

http://localhost:8787/mcp

Local development uses AUTH_MODE=local-bearer by default. Production ChatGPT connector deployments should use OAuth.

For the implementation-aligned authentication model, see docs/auth/README.md.

Configuration

Both wrangler.jsonc and wrangler.example.jsonc are tracked and must stay structurally in sync with placeholders only. Real deployment values (worker host, Auth0 tenant, KV namespace ids) belong in gitignored wrangler.deploy.jsonc — copy from wrangler.deploy.example.jsonc. pnpm run repo:safety enforces structural parity and blocks live values in tracked Wrangler files.

On a fresh clone:

cp wrangler.example.jsonc wrangler.jsonc
cp wrangler.deploy.example.jsonc wrangler.deploy.jsonc

Fill wrangler.deploy.jsonc with at least:

• AWS_REGION

• AWS_ALLOWED_REGIONS

• AUTH_MODE

• MCP_RESOURCE_URL

• OAUTH_ISSUER

• OAUTH_AUDIENCE

• OAUTH_JWKS_URI

• OAUTH_REQUIRED_SCOPES

• kv_namespaces[].id

Important URL model:

ChatGPT Connector Server URL: https://<worker-host>/mcp
MCP_RESOURCE_URL:              https://<worker-host>
OAUTH_AUDIENCE:                https://<worker-host>
OAuth protected metadata:      https://<worker-host>/.well-known/oauth-protected-resource

MCP_RESOURCE_URL and OAUTH_AUDIENCE must use the Worker origin only. Do not append /mcp to those values.

Authentication lifecycle and route responsibilities are documented in docs/auth/README.md, docs/auth/oauth-lifecycle.md, and docs/auth/token-validation.md.

Tool exposure (optional)

Self-hosted deployments can limit which MCP tools are exposed without changing source code. Prefer enabling fewer tools for least privilege.

Tool packs:

core:           search, fetch, get_gateway_status
cost:           get_aws_cost_summary, get_aws_cost_by_service, get_budget_status
inventory:      list_ec2_instances, list_lambda_functions, list_s3_buckets, get_ecr_image_status, compare_ecs_task_image_with_ecr
observability:  get_cloudwatch_alarms, get_cloudwatch_logs, get_cloudwatch_alarm_summary, get_recent_log_errors, list_log_groups, get_ecs_service_health, list_ecs_tasks, get_recent_stopped_ecs_tasks
database:       get_rds_instance_health, get_rds_metrics
aggregates:     aws_account_overview, aws_cost_overview, aws_observability_overview (opt-in)
security:       check_ssm_parameter_inventory, get_s3_bucket_posture, get_ses_configuration_status, get_sns_topic_status, get_eventbridge_rules_status (opt-in)
application-ops: list_application_profiles, get_application_environment_overview, get_application_compute_status, get_application_database_status, get_application_logs, get_application_secret_inventory, get_application_artifact_status, get_application_alerting_status, get_application_cost_status (opt-in)

The aggregates pack is opt-in. Enable it when you want bounded overview tools that compose existing inventory, cost, observability, and database capabilities. The security pack is opt-in for SSM parameter inventory, S3 posture, SES configuration metadata, SNS topic status, and EventBridge/Scheduler status. The application-ops pack is opt-in for KV-backed application profile discovery and profile-driven operational summaries. Default deployments expose 21 MCP tools; enabling aggregates adds three more; enabling security adds five more; enabling application-ops adds nine more.

Exposure rules:

1. The tool's pack must be enabled.

2. The tool must not appear in AWS_MCP_DISABLED_TOOLS.

3. When AWS_MCP_ENABLED_TOOLS is set, only listed tools are exposed (within enabled packs).

4. The tool's risk level must match AWS_MCP_MAX_RISK_LEVEL.

Disabled tools are omitted from tools/list and fail safely if called directly. Unknown pack or tool names fail configuration validation.

Example — cost tools only (no core helpers):

AWS_MCP_ENABLED_TOOL_PACKS=cost

Example — cost tools plus ChatGPT catalog helpers:

AWS_MCP_ENABLED_TOOL_PACKS=core,cost

Example — enable aggregate overview tools:

AWS_MCP_ENABLED_TOOL_PACKS=core,cost,inventory,observability,database,aggregates

Example — default packs (explicit; same as omitting the variable):

AWS_MCP_ENABLED_TOOL_PACKS=core,cost,inventory,observability,database

Example — full read-only operational mode (all generic packs):

AWS_MCP_ENABLED_TOOL_PACKS=core,cost,inventory,observability,database,security,aggregates,application-ops

Example — application profile mode:

AWS_MCP_ENABLED_TOOL_PACKS=core,cost,inventory,observability,database,security,application-ops

AWS IAM setup

Use a dedicated IAM user with only the permissions required by the gateway.

The canonical read-only policy is maintained at infra/aws/iam-readonly-policy.json.

See docs/aws-iam-setup.md for the complete IAM setup flow. For multi-account access with STS AssumeRole, see docs/aws-credentials.md and docs/iam-cross-account.md.

Do not use AdministratorAccess or broad AWS-managed policies for this gateway.

Optional KV cache

Cloudflare KV can cache normalized AWS tool responses to reduce repeated AWS API calls and Cost Explorer usage.

Create the namespace:

wrangler kv:namespace create "AWS_MCP_CACHE"

Then copy the returned namespace id into wrangler.deploy.jsonc.

Default cache TTLs:

The cache is optional for local development and tests. If the binding is absent, tools run without caching.

Application profiles use a separate optional KV binding (AWS_MCP_APP_CONFIG) for saved operational context. Application profiles are optional — do not configure AWS_MCP_APP_CONFIG unless you use the application-ops profile workflow. Profiles are not required for /mcp or generic AWS tools. See docs/application-profiles.md for schema details, docs/aws-tools.md for direct generic tools, and docs/application-profiles.md#cli-workflow for pnpm app-profile:* commands.

Cost Explorer billing estimates: Non-cached ce:GetCostAndUsage requests are estimated at approximately US$ 0.01 per live API call. Cached responses report estimatedCostUsd: 0 and do not make a new Cost Explorer request. These values are approximate gateway estimates only — final AWS billing is determined by your AWS account usage and pricing.

Successful AWS-backed tool responses also expose cache status, AWS request counts, and conservative billing metadata at structuredContent.execution. See docs/mcp-tools.md#execution-metadata.

Deploy to Cloudflare Workers

Prepare deploy-time credentials:

cp .env.deploy.example .env.deploy.local

Fill the required values in .env.deploy.local and deployment values in wrangler.deploy.jsonc, then deploy:

pnpm run deploy:configured

Or deploy code after syncing Worker secrets:

pnpm run sync-secrets
pnpm deploy

pnpm deploy uses wrangler.deploy.jsonc (not tracked wrangler.jsonc). For OAuth production mode, configure OAuth values in wrangler.deploy.jsonc [vars] and use Worker secrets only for credentials and private client secrets.

See docs/deployment.md for the full deployment guide.

Connect to ChatGPT

This gateway is designed for a ChatGPT custom app connector.

In ChatGPT connector setup, use:

Server URL: https://<worker-host>/mcp
Authentication: OAuth
Scope: aws:read

The Worker OAuth resource and audience must be the origin only:

https://<worker-host>

After deploying, configure deployment targets (AWS_MCP_GATEWAY_WORKER_URL, AWS_MCP_GATEWAY_AUTH0_DOMAIN in .env.deploy.local or as script arguments), then run:

pnpm run verify:connector-contract
source .env.deploy.local && pnpm run verify:oauth
pnpm run verify:oauth:authenticated

Then create or refresh the ChatGPT connector. The Actions list should expose all enabled MCP tools from tools/list (18 by default; 21 when the aggregates pack is enabled). Disabled or pack-gated tools do not appear as Actions.

Detailed setup and troubleshooting:

• docs/chatgpt-connector.md

• docs/auth-chatgpt-oauth.md

• docs/chatgpt-connector-smoke-test.md

• docs/chatgpt-connector-production-acceptance.md

Security model

The gateway is intentionally read-only.

Required controls:

• MCP requests must be authenticated.

• AWS credentials must be stored outside Git as Cloudflare secrets.

• IAM permissions must be least-privilege and read-only.

• Tools must be explicit and allowlisted.

• Tool inputs must enforce date, region, and result-size limits.

• AWS responses must be normalized before returning to the client.

• Logs and errors must not expose secrets, AWS access keys, bearer tokens, OAuth tokens, or raw stack traces.

Forbidden in the current scope:

• no run_aws_cli tool;

• no call_any_aws_api or generic AWS API proxy;

• no AWS write or management permissions;

• no raw AWS API responses returned to MCP clients;

• no committed .env, .dev.vars, .env.deploy.local, wrangler.deploy.jsonc, .wrangler/, or real credentials.

For the full security checklist, see SECURITY.md.

AWS operations model

• Generic tools — pass resource names directly (clusterName, logGroupName, dbInstanceIdentifier, …); no profiles required. See docs/aws-tools.md.

• Application profiles — optional saved operational context in KV for the application-ops pack. See docs/application-profiles.md.

• Cross-account IAM — one gateway user plus sts:AssumeRole into read-only target roles. See docs/iam-cross-account.md.

Testing

Minimal local loop:

pnpm run typecheck
pnpm test
pnpm run test:integrity

Full pre-PR / pre-deploy validation:

pnpm run repo:safety
pnpm run output:guardrail
pnpm run verify:connector-contract
pnpm run typecheck
pnpm test
pnpm run test:integrity

• pnpm run repo:safety — tracked files stay public-safe (no local env files, secret-like values, or maintainer deployment defaults in Git).

• pnpm run output:guardrail — production source routes runtime output through src/observability/ and does not call console.* elsewhere.

• pnpm run verify:connector-contract — local ChatGPT Connector contract gate (manifest, policy, capability, exposure, descriptors, tools/list).

Tests are offline by default. A global fetch guard fails any unmocked network request during unit tests.

CI runs repo:safety, output:guardrail, and verify:connector-contract in .github/workflows/ci.yml. Gitleaks secret scanning runs in .github/workflows/secret-scan.yml.

Runtime MCP/auth dependency upgrades must be treated as protocol changes. See docs/dependency-upgrade-contract.md.

Documentation

Repository safety

Safe to commit:

• source code;

• tests;

• documentation;

• tool schemas;

• example IAM policies;

• example environment files;

• Wrangler configuration without secrets.

Never commit:

• AWS access keys;

• Cloudflare API tokens;

• OAuth client secrets;

• bearer tokens;

• .env;

• .dev.vars;

• .env.deploy.local;

• wrangler.deploy.jsonc;

• .wrangler/.

Contributing

Before opening a pull request, run the full pre-PR validation block from Testing (all six commands). When changing MCP descriptors, tool manifests, or connector discovery, pnpm run verify:connector-contract is required.

Use conventional commits:

type(scope): message

Examples:

docs(readme): improve setup guide
feat(mcp): add read-only budget status tool
fix(auth): reject tokens without required scope
security(aws): tighten IAM policy actions

Pull requests that change public tool behavior should update docs/mcp-tools.md and include focused contract tests.

License

MIT. See LICENSE.

Disclaimer

This project is not affiliated with AWS, Cloudflare, OpenAI, or Auth0. Use it with dedicated credentials, least-privilege IAM permissions, and your own security review before production use.