Connect your assistant
Your assistant reads your mail. Let it hand Instant the receipts.
If you already use ChatGPT, Claude or Grok with your mail, connect Instant to it. Your assistant can then send Instant the receipts, bills and invoices it finds, and ask about your books. Instant books them like anything else you send it.
- Your own sign-inYou sign in to Instant and allow your assistant once. No keys to copy.
- Asks and booksIt asks about your books and hands Instant documents to book.
- The rest waits for youPaying, sending and approving stay with you, in Instant.
Connect in a minute
Every assistant uses the same address. You add it once, then sign in to Instant and choose Allow. In Instant, Settings › Your connections opens the right place for each one.
https://app.booksbyinstant.com/api/mcpClaude
This link opens Claude with Instant already filled in.
Add Instant to Claude- In Claude, choose Add, then Connect.
- Sign in to Instant if you are asked, and choose Allow.
- In a chat, turn Instant on under + › Connectors and ask away.
Without the link: Customize › Connectors › Add › Add custom connector, then paste the address.
ChatGPT
- Open Settings › Apps & Connectors and create a connector with the address above. If you don’t see Create, turn on developer mode under Advanced settings first.
- Sign in to Instant when ChatGPT asks, and choose Allow.
- In a chat, pick Instant from the tools and ask away.
Grok
- Open grok.com/connectors, choose New Connector, then Custom, and paste the address above.
- Sign in to Instant when Grok asks, and choose Allow.
Another assistant
Any assistant that can add a remote MCP server with OAuth sign-in can connect. Add the address above as a connector, then sign in to Instant and choose Allow.
What your assistant can do
Ask about your books
Which bills are due, what a supplier was paid, how a month looks. Instant answers from your company, with your role. Questions change nothing, so your assistant doesn’t ask you first.
Hand Instant documents
Up to five files at a time, such as a receipt photo or an invoice PDF. Instant keeps them as your documents and books them. Your assistant asks you before it sends.
Leave the rest to you
It cannot send email or messages, pay, approve, file with an authority, invite people or change a supplier’s bank details. Instant prepares those, and you confirm them in Instant.
The details, when you need them
Where your data goes
What you and your assistant exchange with Instant also passes through your assistant’s provider (OpenAI, Anthropic or xAI), under your own agreement with them. Instant’s own processing stays as Safe AI describes.
The connection is yours alone. Your assistant works in your company with your role, and a colleague can’t use it or see it.
Mail that tries to give orders
Your assistant reads mail that anyone can write. So Instant treats what it brings as information, never as your permission. A message from it can’t approve, pay or send anything, and Instant offers it no tool that could.
Everything it does appears in your activity log, marked as coming from your assistant.
Disconnecting
Remove Instant in your assistant’s connector settings, or disconnect it in Instant under Settings › Your connections. Either one ends the connection.
For developers
- MCP over Streamable HTTP at
https://app.booksbyinstant.com/api/mcp: stateless, POST only, JSON answers. - OAuth 2.1 with dynamic client registration (RFC 7591) and PKCE (S256 only). Metadata at
/.well-known/oauth-protected-resourceand/.well-known/oauth-authorization-server. Return addresses are https, or http on localhost. - Access tokens last an hour. Refresh tokens last 30 days and are used once each.
ask_instanttakes amessageand an optionalthreadId, and only reads (readOnlyHint).send_to_instanttakes amessage, up to five base64files(about 3 MB in all) and an optionalthreadId, and books what it is sent (destructiveHint).- Either answer ends with the
threadId, so the next call continues the same conversation.
Questions
Email us at hello@light.inc.
Last updated 13 November 2026.