Free TierAPI Key AuthOpenAPI Spec
Emma is an email marketing platform that helps businesses create, send, and analyze email campaigns with automation and audience segmentation capabilities.
#8 of 30 in Email · #13 of 89 in Marketing · #27 of 99 in Automation
Checklist Breakdown
13 of 33 checks passed.
14 unscored.
Can an agent find and understand this tool without a web search?
✓
Published OpenAPI/Swagger spec
✗
Has llms.txt or llms-full.txt
✗
Has an MCP server (official or well-maintained)
✗
MCP server listed in a public registry
✓
API reference docs are publicly accessible
✓
Docs include runnable code examples
✓
Has a public changelog or release notes
✓
Has a public status page
Can an agent create an account and get credentials without human intervention?
✗
Signup does not require CAPTCHA
✗
Signup does not require phone verification
✓
Supports API key auth (not only OAuth)
✗
API key obtainable without manual approval
✓
No mandatory billing info to start
✓
Can sign up without creating an organization
Can an agent operate autonomously without upfront payment or contracts?
✓
Has a free tier
✓
Usage-based pricing available
✓
No minimum contract or commitment
✓
Pricing page is public (no 'contact sales')
✓
Free tier sufficient for testing (not just a trial)
How well does the API work for non-human consumers?
—
SDK available in 2+ languages
—
Structured error responses (JSON with error codes)
—
Idempotency support on write endpoints
—
Pagination on list endpoints
—
Webhook/event support
—
Sandbox or test mode available
—
Rate limit headers in responses
—
Consistent REST resource naming
Does the tool fail gracefully when an agent makes a mistake?
—
Meaningful error messages (not just 500)
—
429 responses include Retry-After header
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Documented uptime SLA (99.9%+)
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Graceful degradation under rate limits
—
Request IDs in responses for debugging
—
API versioning supported
Reviewer Notes
Emma has an OpenAPI spec and dual auth methods (API key + OAuth), which aids tooling, but lacks an MCP server and llms.txt for easy discovery. Account creation requires human verification (email confirmation, phone number validation) preventing autonomous signup. The free tier and established API support agent usage once authenticated, but no sandbox environment limits safe experimentation. The main weakness is the friction in initial onboarding—agents cannot self-service accounts, requiring pre-configured credentials.
Let your agents find tools like Emma
Install the Agent Native Registry MCP server. Your agents can search, compare, and score tools mid-task.
claude mcp add --transport http agent-native-registry https://agentnativeregistry.com/api/mcp