# Teardrop

> Teardrop is an open agent platform: a pay-per-call AI tool marketplace with MCP tool serving, A2A agent delegation, AG-UI streaming, and USDC/x402 settlement on Base. Machine clients should start at the agent card, then read the marketplace llms.txt before calling tools.

Teardrop serves two primary A2A interfaces (see the agent card for authoritative URLs): an AG-UI SSE streaming interface and an A2A JSON-RPC interface. Authentication is JWT bearer (SIWE or client-credential onboarding); pay-per-call tools settle in USDC via x402.

## Discovery

- [Agent card (A2A)](https://teardrop.dev/.well-known/agent-card.json): A2A agent card — identity, supportedInterfaces, skills, securitySchemes, billing and marketplace endpoints. Served as `application/a2a+json` with ETag revalidation.
- [MCP server card](https://api.teardrop.dev/.well-known/mcp/server-card.json): MCP server descriptor for the Teardrop tool gateway.
- [Registry benefits](https://api.teardrop.dev/.well-known/registry-benefits.json): benefits for agents registered in the Teardrop marketplace directory.
- [Tool reputation](https://api.teardrop.dev/.well-known/reputation.json): aggregate public reputation for published tools.
- [JWKS](https://api.teardrop.dev/.well-known/jwks.json): signing keys used to verify issued tokens.

## API

- [API reference](https://api.teardrop.dev/docs): public REST reference for agent runs, billing, marketplace, wallets, and more.
- [Marketplace guide (llms.txt)](https://teardrop.dev/marketplace/llms.txt): LLM-readable catalog of public tools with descriptions, prices, and per-tool links.
- [Marketplace catalog (JSON)](https://api.teardrop.dev/marketplace/catalog): machine-readable tool catalog. Query params: `q`, `org_slug`, `sort`, `limit`, `cursor`.
- [Billing pricing](https://api.teardrop.dev/billing/pricing): current per-endpoint pricing used by x402 settlement.

## Protocols

- [A2A JSON-RPC](https://api.teardrop.dev/message:send): send a message / task to the Teardrop agent (see agent card for the authoritative interface entry).
- [AG-UI SSE](https://api.teardrop.dev/agent/run): streaming agent runs with tool-call and UI events.
- [MCP gateway](https://api.teardrop.dev/tools/mcp): serve Teardrop marketplace tools over Model Context Protocol.

## Payments

- x402: per-call USDC settlement over HTTP 402 on Base (`eip155:8453`), scheme `exact`. Payment endpoint and pricing are declared in the agent card capabilities.

## Optional

- [Marketplace index](https://teardrop.dev/marketplace): public HTML catalog of all tools, linking to per-tool and per-author pages.
- [Landing page](https://teardrop.dev/): entry point — agent card command plus the public GET surface.
- [Operator console login](https://teardrop.dev/login): human sign-in (email or SIWE) for org administration — spend limits, allowlists, credentials.