Free TierAPI Key AuthOpenAPI Spec
Percy is a visual regression testing platform that automatically detects changes in web application UIs by comparing screenshots across builds. It integrates with CI/CD pipelines to catch unintended visual changes.
#14 of 28 in Testing · #6 of 9 in Ci Cd
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
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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?
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Meaningful error messages (not just 500)
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429 responses include Retry-After header
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Documented uptime SLA (99.9%+)
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Graceful degradation under rate limits
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Request IDs in responses for debugging
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API versioning supported
Reviewer Notes
Percy has a documented REST API and OpenAPI spec, making tooling integration feasible for CI/CD automation. However, account creation requires OAuth or manual signup with email verification, blocking programmatic agent onboarding. The free tier supports limited builds monthly, but lacks an MCP server and llms.txt for agent discovery. Reliability is solid for a SaaS testing platform, but the visual testing nature means agents would struggle to autonomously trigger meaningful tests without UI knowledge—better suited as an integration target than a primary agent tool.
Let your agents find tools like Percy
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claude mcp add --transport http agent-native-registry https://agentnativeregistry.com/api/mcp