E-signature MCP server for AI assistants

Server details

Connect your assistant

• ClaudeClaude on the web, desktop and mobile, and Claude Code.
• ChatGPTAdd SignWith as an app in developer mode.
• CursorOne click, or mcp.json with an API key.
• VS CodeGitHub Copilot agent mode, one click or mcp.json.

Any other client that supports remote MCP servers over Streamable HTTP works the same way: give it the URL above, and either sign in with OAuth or send an API key header.

What you can ask

Once SignWith is connected, ask in plain language:

• "Send the consulting agreement template to [email protected]."
• "Which lease requests are still waiting for a signature?"
• "Remind the signers on the Riverside lease."
• "Is this PDF really signed with SignWith?"
• "Turn this contract into a template with signature lines for the client and me."

When an assistant writes or edits a document for you, it uses text tags to place the signature and other fields.

Each tool runs the matching endpoint of the SignWith API, with the same rules, credits and errors. Anything an assistant creates is recorded with source: "mcp", and you can see every call under Settings → API activity.

Two ways to sign in

OAuth (recommended). Add https://app.signwith.co/mcp as a connector in your assistant. It sends you to SignWith to sign in and approve the connection, choosing Full access or View only. No key is pasted anywhere. Manage or disconnect apps in Settings → Connected apps.

API key. Clients that let you set request headers can send an API key instead:

Authorization: Bearer sw_live_...

Access and confirmations

A View only connection or a read-only API key lists only the tools it can use. The assistant can look at templates and signature requests, verify PDFs and send feedback, but it can't send, change or cancel anything.

Tools that email people or can't be undone (sending, reminding, canceling and archiving) are marked for the assistant to confirm with you first. Most clients, including Claude and ChatGPT, ask you before running a tool like this unless you've chosen to always allow it.

Credits

Sending through an assistant uses credits exactly like the API: see credits and billing. If an account runs out, the assistant can show the credit packs and give you a checkout link to pay in your browser; it never pays itself. Inside ChatGPT the purchase tools aren't offered, and the assistant asks you to add credits in SignWith instead.

When a tool call fails

A failed call returns a normal result with isError: true and the API's error code and message, so the assistant can explain the problem or fix its arguments and try again. Calls missing required arguments fail the same way and name the missing arguments. Two codes only come from MCP: insufficient_scope when a View only connection tries to change something, and not_available for a tool that isn't offered to that app. All codes are on the errors page.

Building your own MCP client? The OAuth and protocol reference has the authorization flow and protocol details.