Buy from an MCP client

@zanora/mcp is an MCP server that runs locally over stdio. It gives the model ten tools. Two of them matter most: zanora_discover finds something to buy, and zanora_invoke pays for it and calls it.

Add it to your client

MCP config

{
  "mcpServers": {
    "zanora": {
      "command": "npx",
      "args": ["-y", "@zanora/mcp"],
      "env": {
        "ZANORA_API_KEY": "zk.akey_…",
        "ZANORA_AGENT_KEY_FILE": "/absolute/path/to/agent-key.pem",
        "ZANORA_MAX_PRICE_MINOR": "500"
      }
    }
  }
}

Client	Where the config goes
Claude Desktop	`~/Library/Application Support/Claude/claude_desktop_config.json` (macOS), `%APPDATA%\Claude\claude_desktop_config.json` (Windows)
Claude Code	`.mcp.json` in the project, or `claude mcp add zanora -- npx -y @zanora/mcp`
Cursor	`.cursor/mcp.json`
Anything else	the client's MCP server config: command `npx`, args `["-y", "@zanora/mcp"]`

Restart the client. The server checks the configuration at startup and prints a banner to stderr. A misconfiguration fails immediately with the name of the variable at fault.

You need a wallet first

The config uses a workspace API key and the private key of an agent wallet. If you don't have them, follow Create a workspace and Wallets and agent keys, then fund the wallet.

Configuration

Variable	Required	Meaning
`ZANORA_API_KEY`	yes	a workspace key. Use a dedicated agent key rather than the root one (see Approvals)
`ZANORA_AGENT_KEY_FILE`	yes¹	path to the agent's ed25519 private key PEM
`ZANORA_AGENT_KEY`	yes¹	the PEM inline, if you can't use a file
`ZANORA_WALLET_ID`	no	only needed when the workspace has more than one agent wallet. With several and none named, it refuses to start and lists them
`ZANORA_MAX_PRICE_MINOR`	no	a per-call ceiling in cents. Set one. A tool argument can lower it for one call but never raise it
`ZANORA_GATEWAY_URL`	no	defaults to `https://api.zanora.dev`
`ZANORA_AGENT_ID`	no	the agent name on payment proofs (defaults to the wallet id)
`ZANORA_APPROVAL_ELICITATION`	no	`on` (default) or `off`: whether to ask the user about held spends
`ZANORA_ALLOW_LOCAL_PACKAGES`	no	packages this agent may run to buy them. Unset means none. See Running seller packages
`ZANORA_SELLER_HEADERS`	no	JSON keyed by seller origin, for sellers behind their own auth: `{"https://seller.example":{"authorization":"Bearer …"}}`

¹ One of the two.

The tools

Tool	Does	Spends
`zanora_discover`	ranked marketplace search: price, seller reputation, request schema
`zanora_capability`	resolves a known capability id (from an earlier session, a receipt, or the user) so it can be invoked
`zanora_invoke`	pays a capability's price and returns its response and signed receipt	✓
`zanora_wallet_balance`	balance and available balance
`zanora_wallet_ledger`	every charge, refund and deposit
`zanora_purchases`	what this wallet bought, from its receipts. Pages with `after`
`zanora_receipt`	fetches a receipt and checks its signature
`zanora_rate_provider`	rates a seller 1–5 for a purchase this wallet made
`zanora_deposit_addresses`	where money can be sent to this wallet
`zanora_approval_status`	whether a person approved a held spend

The loop is discover → invoke with the capabilityId from a result. The server remembers endpoints from discovery, so the model never types a URL. An id it hasn't seen is an error, not a guess, and zanora_capability resolves it properly. REST and MCP capabilities are both bought with zanora_invoke.

Every tool returns typed structuredContent along with text. zanora_invoke reports four named progress steps if the client sends a progress token.

When the answer is "no"

Refusals come back as readable tool results, and nothing is charged:

Result	The model should
`POLICY_DENIED`	pick another capability. Never retry the same one
`APPROVAL_REQUIRED` + id	report the id and stop. If the client supports it, the user is asked directly (see Approvals)
`APPROVAL_DENIED`	stop. Don't ask again
`INSUFFICIENT_FUNDS`	stop and tell the user where to send money (`zanora_deposit_addresses`). With elicitation, the user is shown the shortfall and the addresses, and the purchase is retried once the balance has actually changed
`PRICE_ABOVE_CLIENT_LIMIT`	the price is over `ZANORA_MAX_PRICE_MINOR`. Choose something cheaper

Resources

The server also offers resources a person can browse without asking the model: zanora://wallet (balance) and zanora://purchases (recent receipts). They return the same data as the matching tools.

Try it

Ask the model:

Output

Search Zanora for invoice OCR under $2, buy the cheapest one on
https://example.com/invoice.png, verify the receipt, and rate the seller.

Safety model

The key file is the spending authority. Give each agent its own wallet, funded with what you'd accept losing to it.
The limits are on the server. Budgets and policies are checked by the platform. ZANORA_MAX_PRICE_MINOR is an extra limit on your side, not a replacement.
Buying and reading only. The server can't create wallets, move money between them, change policies or read another tenant's data.
Running code is off by default. A search result can never cause a seller's code to run on your machine.

#Add it to your client

#Configuration

#The tools

#When the answer is "no"

#Resources

#Try it

#Safety model