Connect Claude.ai to AssinaJá

By the end of this guide, you ask Claude to send a document for signature and it sends it.

There are two sides: first create the key in AssinaJá, then point Claude at it. The order matters — the authorisation asks you to pick a key, and if none exists the process stops halfway.

Before you start

• In AssinaJá: be Owner or Admin. That is who can create API keys — see Roles and permissions.
• In Claude.ai: a plan that allows custom connectors. As of this guide, the Free, Pro, Max, Team and Enterprise plans do, with Free limited to one connector.

1. Create the key in AssinaJá

Under Settings → API Keys, choose New API Key.

1. Name — something that identifies the connection, e.g. Claude.ai. You will need to recognise it six months from now.
2. Expiry date — optional, but a key with an expiry is a key that gets reviewed.
3. Access — tick only what you want the assistant to do.

Start without the publish permission

Tick Templates — read, Documents — read and Documents — create. Leave Documents — publish out.

With that combination Claude prepares everything and leaves the document as a draft — you are the one who presses send, in the application. Once you know how it behaves, add the publish permission if you want it.

Choose Create key.

The key is shown only once

Copy this key and store it somewhere safe. It will not be shown again.

For Claude.ai you will not actually need to copy it — the connection is over OAuth and the key is picked from a list. Save it anyway: if you later want the same integration in Claude Code, that is where it is needed.

2. Add the connector in Claude.ai

The steps below are from the Claude.ai interface in August 2026. If the names do not match, the official guide is at support.claude.com.

On an individual account (Free, Pro or Max):

1. Open Customize → Connectors.
2. Choose +, then Add custom connector.
3. For the server address, paste:

   https://app.assinaja.pt/mcp

4. Choose Add.

On a Team or Enterprise account, the connector is added once by the owner, under Organization settings → Connectors → Add, going through Custom and choosing Web. After that, each member goes to Customize → Connectors and chooses Connect to authenticate with their own account — and therefore with whichever key they pick.

Leave “Advanced settings” empty

Claude.ai offers optional OAuth Client ID and Client Secret fields. Leave them blank: the AssinaJá server registers the client automatically. Filling them with made-up values makes the connection fail.

3. Authorise

When you add the connector, Claude opens the AssinaJá authorisation page. It is titled Ligar Claude ao AssinaJá and has two steps.

If you are not signed in yet, you sign in first.

Step 1 of 2 — choose the API Key to use

Open the list — it shows — select an API Key — — and pick the key you created. Then Continue.

You have no active API Key.

Create one in the backoffice under Settings → API Keys and retry the connection.

If you see this, you skipped step 1 of this guide.

Step 2 of 2 — confirm the access you are granting

Here you see the exact list of what the key allows. It is your last chance to notice you ticked one permission too many.

By confirming, it is recorded that you authorized Claude to use this key. You can cut the access at any time by suspending or deleting the key under Settings → API Keys.

Choose Authorize access. You get Establishing the connection — “Aguarde — estamos a finalizar e a devolvê-lo ao Claude. Não feche esta janela.” — and are returned to Claude automatically.

4. Confirm it works

In the conversation, ask for something that only works with the connection up:

List the templates available in AssinaJá.

You should get your organisation’s real templates. If you get a generic answer about AssinaJá with no list, the connector is not being used — check that it is enabled under Customize → Connectors.

A second, more useful test:

Create a document from template X for João Silva (joao@exemplo.pt) and leave it as a draft.

Then go to the document list and see if it is there. That is how you verify the key is bound to the right organisation.

5. Cut access

You do not disconnect a connector like this from Claude’s side — you do it from the key’s side.

Under Settings → API Keys, Suspend the key: “While suspended, the key no longer authenticates until it is reactivated.” Claude’s access drops on the next request.

Suspending is reversible and deleting is not. If you are just testing, or suspicious of something, suspend.

If it goes wrong

What you see	What to do
You have no active API Key.	The key does not exist, is suspended, or expired. Create or reactivate one.
Claude shows no AssinaJá tools	The connector is not enabled, or the key has no permissions ticked.
Claude sees documents but cannot create them	Documents — create is missing from the key. Edit it under Settings → API Keys.
Claude creates but nothing is sent	Expected without Documents — publish, or with the draft policy enabled.
The connection fails when adding the connector	Check the OAuth Advanced settings were left empty.

A tool the key does not allow does not appear to the assistant, rather than failing when called. So the answer to “Claude cannot do X” is almost always a missing permission on the key, not a fault.

Related

• What MCP is — the security model behind this
• Connect ChatGPT to AssinaJá
• Create an API key
• Deliver a file to an assistant