Lago

Fair

Agent Native Score

Free TierAPI Key AuthOpenAPI Spec

Lago is an open-source billing and metering platform that enables usage-based pricing, subscription management, and invoicing. It provides APIs for tracking consumption, managing customers, and automating billing workflows.

Categories: Billing · Metering · Invoicing

#7 of 26 in Billing · #2 of 5 in Metering · #2 of 3 in Invoicing

Checklist Breakdown

13 of 33 checks passed. 14 unscored.

Discovery 63%

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

Auth & Onboarding 50%

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

Pricing 100%

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)

Agent Tooling Not yet scored

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

Reliability Not yet scored

Does the tool fail gracefully when an agent makes a mistake?

— Meaningful error messages (not just 500)

— 429 responses include Retry-After header

— Documented uptime SLA (99.9%+)

— Graceful degradation under rate limits

— Request IDs in responses for debugging

— API versioning supported

Reviewer Notes

Lago has solid API documentation and an OpenAPI spec, making it relatively discoverable for agents. However, it lacks an MCP server and llms.txt file, requiring agents to parse specs manually. Account creation requires human interaction (email verification, organization setup), limiting autonomous signup. The REST API is well-structured with good error handling, but rate limiting and error message clarity could be stronger. The free tier and sandbox environment are excellent for agent testing, though production reliability metrics are not widely published. Strength: strong OpenAPI documentation and free tier. Weakness: no agent-native integrations (MCP) and signup friction.

Lago

Let your agents find tools like Lago