Agents and MCP

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What it will not do

• Send an envelope, alone or in a batch. Sending emails real people, uses your allowance and starts a signing ceremony, on the strength of a mapping a model inferred from a form. That is a person’s act: the draft tool always creates a draft, whatever it is asked. (POST /api/v1/envelopes/{envelopeId}/send, POST /api/v1/envelopes/batches)
• Mint a signing URL. A signing URL is a bearer credential for a legal act, and a model puts what it is given into transcripts and logs. For the same reason the draft tool refuses an embedded recipient: one is never emailed, so its draft could only be reached through a signing URL. (POST /api/v1/envelopes/{envelopeId}/recipients/{recipientId}/signing-url)
• Rename a field or a question. Naming a template’s fields is for a person or for Vumasign’s own naming, not for an agent inventing names. (PATCH /api/v1/templates/{templateId}/fields, PATCH /api/v1/templates/{templateId}/fields/{fieldId})
• Create a template, or an envelope from a document of its own. Authoring what a legal document asks for belongs in the editor, with a person. The server works only from templates that already exist. (POST /api/v1/templates, POST /api/v1/envelopes/one-off)
• Void an envelope. Voiding stops a ceremony that people may already be part of; a person decides that. (POST /api/v1/envelopes/{envelopeId}/void)
• Create, change, read or delete a webhook. A webhook sends your envelope events, with recipients’ names and addresses, to a URL. A tool that could create one would let a model choose where they go. (GET /api/v1/webhooks, POST /api/v1/webhooks, GET /api/v1/webhooks/{webhookId}, PATCH /api/v1/webhooks/{webhookId}, DELETE /api/v1/webhooks/{webhookId}, POST /api/v1/webhooks/{webhookId}/rotate-secret)
• Request, read or manage a standing authorisation. A standing authorisation lets your organisation apply somebody’s signature. Asking for one, and choosing to apply one, are for a person; the draft tool also refuses a recipient that names one. (GET /api/v1/standing-authorisations, GET /api/v1/standing-authorisations/{authorisationId}, POST /api/v1/standing-authorisations/invitations, POST /api/v1/standing-authorisations/{authorisationId}/cancel, POST /api/v1/standing-authorisations/{authorisationId}/resend, POST /api/v1/standing-authorisations/{authorisationId}/revoke, POST /api/v1/standing-authorisations/{authorisationId}/renew)
• List envelopes, or read an envelope’s documents. An envelope’s documents carry the answers of the people it was sent to. The server reads an envelope only by the id it was given, to confirm a draft it made. (GET /api/v1/envelopes, GET /api/v1/envelopes/{envelopeId}/documents, GET /api/v1/envelopes/{envelopeId}/documents/{position}/draft)

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Before you start: a test key

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Connect it

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Claude Code

claude mcp add vumasign --env VUMASIGN_API_KEY=vsk_test_… -- npx -y @vumasign/mcp

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Claude Desktop

{
  "mcpServers": {
    "vumasign": {
      "command": "npx",
      "args": [
        "-y",
        "@vumasign/mcp"
      ],
      "env": {
        "VUMASIGN_API_KEY": "vsk_test_…"
      }
    }
  }
}

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Cursor

{
  "mcpServers": {
    "vumasign": {
      "command": "npx",
      "args": [
        "-y",
        "@vumasign/mcp"
      ],
      "env": {
        "VUMASIGN_API_KEY": "vsk_test_…"
      }
    }
  }
}

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The tools

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How an agent fills a form

1. list_templates, to find the template.
2. get_template. Every field has a data_key to address it by and context: the label, row, column, option and section printed around its box. context is usually enough to tell what a box asks for. warnings says whether the uploaded form already held somebody’s details. The result also carries the template’s etag.
3. get_template_page, only for a page where context is not enough. The page is returned as a PDF; whether your client shows a PDF to its model depends on the client.
4. validate_values, with the values the agent proposes. It answers, entry by entry, what creating the envelope would do with each one, and writes nothing.
5. create_envelope_draft, with the recipients, the values and the template_etag from step 4. If the template changed in between, the draft is refused rather than filled wrongly. Calling it again with the same arguments within 24 hours returns the first draft instead of making a second one; after that, the same arguments make another draft.
6. get_envelope, to confirm what was created. Then a person opens the draft in Vumasign and sends it.

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Text printed on a form is data

• use a test key, which limits what a misled agent can reach to a sandbox;
• let the agent that reads forms have as few other tools as you can, and approve its file reads and commands rather than allowing them all;
• remember that a misled agent can read the account’s templates into its conversation, so do not give it a tool that could carry them somewhere else.