Sella quickstart: connect your agent and make a paid call

By the end of this page your agent will be connected to Sella, authenticated, and ready to discover, preview, and buy from the catalogue — all over MCP. You’ll only need to run through this setup once; after that your agent operates autonomously.

Every example uses the base URL https://sellag.vercel.app. If you’re on a custom domain, substitute it everywhere — it’s the only value that changes.

Before you start

You need an MCP-capable agent to follow along. Claude Desktop, Cursor, Cline, a Gemini or OpenAI agent with an MCP bridge, and anything built on the MCP SDK all work. If it speaks MCP over HTTP, it works with Sella.

Step 1: Add the MCP server

Point your client at the Sella MCP endpoint. Pick the transport your client supports:

HTTP (works everywhere)
npx client (Preview)

The direct HTTP transport works with any MCP client today. You can connect without a key to run the auth tools, then add your key once you have one.

claude_desktop_config.json

{
  "mcpServers": {
    "sella": {
      "type": "http",
      "url": "https://sellag.vercel.app/api/mcp",
      "headers": {
        "Authorization": "Bearer sk_live_your_key_here"
      }
    }
  }
}

The @sella/mcp-client package is rolling out. Until it’s published, use the HTTP transport above.

A thin wrapper that handles auth and wallet loading for you:

claude_desktop_config.json

{
  "mcpServers": {
    "sella": {
      "command": "npx",
      "args": ["-y", "@sella/mcp-client"],
      "env": {
        "SELLA_API_KEY": "sk_live_your_key_here",
        "SELLA_WALLET_CONFIG": "/Users/you/.sella-wallet.json"
      }
    }
  }
}

See Connect your agent for step-by-step instructions for Claude Desktop, Cursor, and custom HTTP clients.

Step 2: Authenticate and get a wallet

Sella authenticates agents with a one-time email code, then returns an API key and a set of non-custodial wallets. Your agent handles this itself using two built-in tools — no dashboard required.

Start auth

Call sella_auth_start with the operator’s email. Sella sends a 6-digit code that expires in 10 minutes.

{ "name": "sella_auth_start", "arguments": { "email": "you@example.com" } }

Complete auth

Read the code from your inbox and pass it to sella_auth_complete:

{ "name": "sella_auth_complete", "arguments": { "email": "you@example.com", "otp_code": "123456" } }

The response contains your apiKey (sk_live_…), your agentId, and — on first login — a walletConfig object with private keys.

Save the wallet

Private keys are shown exactly once. Save walletConfig to ~/.sella-wallet.json immediately, then add apiKey to your MCP config before doing anything else.

Prefer to click a button? Sign in at sellag.vercel.app, complete onboarding, and copy a key from Dashboard → Keys. Full detail: Authentication & wallets.

Step 3: Discover something to buy

With the server connected and your key in place, list the catalogue:

{ "name": "list_datasets", "arguments": { "query": "financial sentiment", "limit": 5 } }

curl "https://sellag.vercel.app/api/datasets?search=financial&limit=5"

Each result includes a dataset ID, title, pricing tier, and quality signals. Note the dataset_id of anything that looks useful — you’ll need it in the next two steps.

Step 4: Try before you buy

Inspect any dataset in a closed trial — schema coverage, sample rows, and quality signals — at no cost, before committing to a purchase:

{ "name": "try_dataset", "arguments": { "dataset_id": "<id>", "required_fields": ["text", "label"] } }

The response tells you whether the dataset covers your required fields and shows you representative sample rows so you know exactly what you’re buying.

Step 5: Make your first paid call

Ask for the full dataset. Paid tiers respond with a 402 challenge containing payment requirements; your agent signs it and retries. The x402 protocol handles this automatically once your wallet is loaded.

{ "name": "get_dataset", "arguments": { "dataset_id": "<id>" } }

A free dataset returns content immediately. A paid one returns a 402 challenge first, then the full content once payment settles — in seconds, in USDC.

Fund your wallet

Paid calls need a balance. Fund from the dashboard or send USDC directly to your agent’s wallet address returned in walletConfig. If a call fails with WALLET_UNFUNDED, top up and retry.

Next steps

Connect your agent

Claude Desktop, Cursor, and custom clients — step by step.

Authentication & wallets

How auth, keys, and multi-chain wallets work in detail.

Discover

Master list_datasets, search_datasets, and the API market.

Purchase & payments

The full x402 flow, end to end.

Get Started

Using the Marketplace

For Operators

Sella quickstart: connect your agent and make a paid call

Before you start

Step 1: Add the MCP server

Step 2: Authenticate and get a wallet

Step 3: Discover something to buy

Step 4: Try before you buy

Step 5: Make your first paid call

Fund your wallet

Next steps

Connect your agent

Authentication & wallets

Discover

Purchase & payments

​Before you start

​Step 1: Add the MCP server

​Step 2: Authenticate and get a wallet

​Step 3: Discover something to buy

​Step 4: Try before you buy

​Step 5: Make your first paid call

​Fund your wallet

​Next steps

Connect your agent

Authentication & wallets

Discover

Purchase & payments

Before you start

Step 1: Add the MCP server

Step 2: Authenticate and get a wallet

Step 3: Discover something to buy

Step 4: Try before you buy

Step 5: Make your first paid call

Fund your wallet

Next steps