# Fangst

Fangst provides APIs for getting input, files, and approvals from people. Software or an authorized AI agent creates a hosted request, receives a URL, gives that URL to a person through an available channel, and reads the structured result through the API or a signed webhook.

## Canonical resources

- Product overview: https://fang.st/
- API guide and complete v1 endpoint list: https://fang.st/api/
- AI agent setup and examples: https://fang.st/ai-agents/
- Human-in-the-loop API: https://fang.st/human-in-the-loop/
- MCP server: https://fang.st/mcp/
- MCP forms: https://fang.st/mcp-forms/
- Forms API: https://fang.st/forms-api/
- File Request API: https://fang.st/file-request-api/
- Approval Workflow API: https://fang.st/approval-workflow-api/
- Human Review API: https://fang.st/human-review-api/
- Human Task API: https://fang.st/human-task-api/
- Pricing: https://fang.st/pricing/
- Security and response retention: https://fang.st/security/
- Privacy and website measurement: https://fang.st/privacy/
- OpenAPI 3.1 contract: https://fang.st/openapi.yaml

## Requirements for an AI agent

- HTTP access to the Fangst service
- A Fangst API token sent as Authorization: Bearer <FANGST_API_TOKEN>
- A separate email, chat, SMS or other channel for giving request.hosted_url to the person; Fangst does not send the message

## Request sequence

1. POST /v1/requests with the required fields, files, metadata and optional webhook. A webhook requires its signing secret.
2. Read request.id and request.hosted_url from the response.
3. Give request.hosted_url to the person through an available channel.
4. The person submits the hosted form.
5. Poll GET /v1/requests/:id/submissions or handle the signed submission.completed webhook.
6. After copying the result, DELETE /v1/submissions/:id to remove its content and files from active storage immediately.

## Agent tools

- request_human_input / get_human_input
- request_human_approval / get_human_approval

The Streamable HTTP endpoint is https://api.fang.st/mcp and implements MCP
2026-07-28. Creation tools require requests:write. Polling tools require both
requests:read and submissions:read. Creation requires a stable idempotency_key.
The agent must send the returned private hosted_url through its own channel.
An approval is bound to subject_id and revision_id, but is a decision by the
link holder rather than an identity-verified electronic signature.

All management endpoints and attachment downloads require the Bearer token. The person uses only the hosted URL and does not need a Fangst account. Treat webhook deliveries as retryable and potentially duplicated; use stable event and delivery ids.