What MCP is
MCP — the Model Context Protocol — is an open standard that lets an AI assistant use external services. Without it, an assistant can only talk: it can draft you a contract, but it cannot send it for signature. With it, it has tools.
AssinaJá runs an official MCP server. Once connected, you can ask the assistant in plain language to prepare a document from one of your templates, tell you who has not signed yet, or fetch the signed PDF.
What changes in practice
Section titled “What changes in practice”Signature work is repetitive: take a template, fill the same fields with data that lives somewhere else, pick the signers, send, then keep checking who is missing. That gap is what MCP closes.
It works where you already are. If you are drafting a proposal in a conversation with the assistant, the document leaves from that conversation. No exporting, no switching tabs, no re-uploading the file.
The assistant reads your templates. It queries your organisation’s real templates — with the signers and merge fields actually defined there — rather than inventing a format.
It is for asking, not only for doing. “Which documents have been waiting for signature for more than a week?” is a question the assistant answers from the real list.
It is the same engine. MCP tools call the same services as the public API — there is no second implementation with different rules. What is forbidden in the application stays forbidden here.
Two ways to connect
Section titled “Two ways to connect”| Method | For |
|---|---|
| OAuth | Web assistants: Claude.ai, ChatGPT, Copilot, Grok |
X-Api-Key header |
Local tools and automation: Claude Code, Cursor, CI |
Web assistants do not let you set your own headers, so they use OAuth. Those are the connections described in Connect Claude.ai and Connect ChatGPT.
The server address is the same either way:
https://app.assinaja.pt/mcpLocal tools, via the header
Section titled “Local tools, via the header”For Claude Code, for instance, the connection is a single command with the API key travelling in the header:
claude mcp add --transport http assinaja https://app.assinaja.pt/mcp \ --header "X-Api-Key: ajk_live_..."The security model
Section titled “The security model”This is the part that sets the integration apart, and it is worth understanding before connecting anything.
The assistant never reaches your account
Section titled “The assistant never reaches your account”Even over OAuth, what is issued is not access to your user account. It is access bound to one specific API key. The authorisation page says so itself:
This AI assistant is asking for access to your organization. Access goes through an API Key — the assistant can only do what that key allows, and it never accesses your account.
If the key can only read documents, that is what the assistant can do — there is no route from there to anything else.
The assistant only sees what the key allows
Section titled “The assistant only sees what the key allows”Filtering happens before the assistant decides anything. When it asks the server which tools exist, the answer is already cut down to the key’s permissions: a tool outside that scope does not appear in the list at all, rather than being refused when called.
In practice, an assistant connected with a key lacking Documents — publish does not even know publishing is possible.
Consent is recorded
Section titled “Consent is recorded”Authorising is not a click that disappears. Who authorised, which key, which assistant, which permissions, when, and from what address are all stored. You see that record under Settings → API Keys, in the Authorized to AI assistants section:
Consent record (evidence). To cut an assistant’s access, suspend or delete the key.
Cutting access is immediate
Section titled “Cutting access is immediate”The key is revalidated on every request. Suspending, expiring or deleting it cuts the assistant off at once — no waiting for a session to end.
That answers the most uncomfortable case: if you distrust a connection, suspend the key and see what breaks. Suspending is reversible.
Rules the server imposes on the assistant
Section titled “Rules the server imposes on the assistant”The server sends safety instructions the assistant receives before acting: signer codes belong to the template and must never be invented; publishing emails signers immediately and cannot be undone, so it requires explicit confirmation in the conversation; and a failed creation is never retried blindly, because a second call creates a second document and a second batch of emails.
Usage limit
Section titled “Usage limit”60 requests per minute per credential, shared with the public API.
What the assistant can do
Section titled “What the assistant can do”The available tools depend on the permissions ticked on the key. The names on the right are the ones you see in the assistant.
| Key permission | The assistant can then |
|---|---|
| Templates — read | List templates · Get template details |
| Documents — read | List documents · Get document details · Get document overview · Get signing links · Download document file |
| Documents — create | Create document · Create document from template · Create document from Word template · Create upload link · Get upload link status |
| Documents — publish | Publish draft and notify signers |
| Documents — archive/delete | Archive document · Delete document · Delete draft |
| Organization — read | Get organization · Get subscriptions and plan features |
| Analytics — read | Analytics overview · Usage metrics · Metric over time · Metric breakdown · Signing funnel · Adoption and seats · Metric catalog |
Files on your own computer
Section titled “Files on your own computer”The assistant cannot reach files on your disk. When it needs one, it creates a delivery link — you open it, upload the file, and it carries on. See Deliver a file to an assistant.
The limits
Section titled “The limits”Analytics are off by default. Whether an assistant may read the organisation’s numbers is a separate decision, under Settings → Policies:
Whether assistants connected over MCP may read this organization’s figures. Off by default. It never grants access to documents, content or keys — only aggregated metrics, and every request is written to the audit trail.
An assistant can get things wrong. Reading the right documents and summarising them badly is a possible failure, and MCP does not solve it. For anything that matters, check in the application before sending.
What it does is done in your name. Documents are created in your organisation and consume your quotas.
Related
Section titled “Related”- Connect Claude.ai to AssinaJá
- Connect ChatGPT to AssinaJá
- Create an API key
- Configure organisation policies — the setting that makes AI-created documents start as drafts