Free TierAPI Key AuthOpenAPI Spec
HelloSign (now Dropbox Sign) is an e-signature platform that allows users to request, sign, and manage digital signatures on documents. It provides APIs for integrating signature workflows into applications.
#2 of 6 in Document Management · #1 of 3 in E Signature
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
—
Documented uptime SLA (99.9%+)
—
Graceful degradation under rate limits
—
Request IDs in responses for debugging
—
API versioning supported
Reviewer Notes
HelloSign has a documented REST API and sandbox environment, which supports agent integration, but lacks an MCP server and llms.txt file, limiting discoverability. Account creation requires human verification (email confirmation, phone, or identity checks), making programmatic signup difficult. The API is reasonably well-structured with good error handling, though documentation could be more agent-friendly. The free tier with sandbox mode is a strength for testing, but production use requires payment. Main weakness: no MCP server and OAuth-first auth makes autonomous operation challenging; main strength: mature API with sandbox testing.
Let your agents find tools like HelloSign
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