Hosted MCP server for Anvil — fill & generate PDFs and run Etch e-signature packets for AI agents. Hosted by usefulapi: connect it to Claude, ChatGPT, Cursor or any MCP client.
Turn on the Anvil connector, then ask in plain words. The AI picks the tools.
For developers and operations teams who fill PDFs and send e-signature packets with Anvil.
Reads an organization by slug or eid and lists its PDF templates (casts) and workflows (welds). Can also show a template's title and version number.
Fetches a workflow (weld) with its forges, which are the form steps with name and slug. Can also check whether one submission is complete and whether it was a test.
Takes the template (cast) eid and your field values, fills the template and returns the finished PDF as base64.
Changes dataBuilds a new PDF from the HTML and CSS or the Markdown sections you give, and returns it as base64.
Changes dataReads an Etch packet by eid: its status and each signer with name, email, status and routing order. Shows who has signed and who has not.
Creates an Etch packet with documents and signers. It is a draft by default and sends nothing. Real signature emails go out only if you turn the draft off. A test mode is available.
Changes dataThe login page asks for your Anvil API key.
Find it in Anvil → Organization Settings → API keys. Your key is used only to call the API on your behalf and to derive a private account id; it is never shown to anyone.
Team and Enterprise: an Owner adds the connector for the organization first.
No Add custom MCP server option? It depends on your account or workspace settings: see OpenAI's guide.
Run this command, then run /mcp in Claude Code to log in:
Add to Cursor or add this to ~/.cursor/mcp.json:
{
"mcpServers": {
"anvil": {
"url": "https://anvil.usefulapi.io/mcp"
}
}
} Add to VS Code or add this to .vscode/mcp.json:
{
"servers": {
"anvil": {
"type": "http",
"url": "https://anvil.usefulapi.io/mcp"
}
}
} Run these commands. The second one opens the login page:
Windsurf, Cline, Zed and other MCP clients: add this URL as a remote MCP server (Streamable HTTP). The client then opens the login page in your browser.
Add only the URL. Do not add an Authorization header or an API key to the client config. The server signs you in with OAuth: the login page asks for your Anvil API key. If the config has such a header, remove it: some clients then send that header instead of the login token, and every call fails with 401.
| Plan | Price | Limit |
|---|---|---|
| Free | $0 | 50 tool calls / month |
| Pro | $9/mo · $90/yr | 10,000 tool calls / month |
| Pro+ | $39/mo · $390/yr | 100,000 tool calls / month |
Each paid plan covers this Anvil server only. Ask your AI to run anvil_upgrade and choose Pro or Pro+, billed monthly or yearly (it returns a Stripe Checkout link). If you already have Pro, ask to change it to Pro+. The change requires your confirmation, keeps your billing interval and charges the price difference for the rest of the period immediately. Cancel any time with anvil_cancel_subscription: your paid plan continues to the end of the paid period, with no refund for the current period, and asking to resume the same plan with anvil_upgrade before then undoes the cancel. Or write to [email protected].
anvil_current_useranvil_get_organizationanvil_get_castanvil_get_etch_packetanvil_get_weldanvil_get_weld_dataanvil_fill_pdfanvil_generate_pdfanvil_create_etch_packetanvil_generate_etch_sign_urlanvil_usage_statusanvil_request_featureanvil_upgradeanvil_cancel_subscriptionList our PDF templates and workflows. Check the steps and a submission of a workflow. Fill a PDF template with your data. Generate a new PDF from HTML or Markdown. Check the signature progress of an Etch packet. Create an Etch signature packet as a draft. See what you can do for the details.
No. usefulapi is an independent service. It is not affiliated with or endorsed by Anvil. The server calls the Anvil API with your own Anvil access, so it sees only the data that your account can see.
Yes. In Claude, add this server's URL as a custom connector. In ChatGPT, add it as a custom MCP server in Plugins. Then log in once. Cursor, VS Code, Claude Code and Codex work too. See the setup steps.
The login page asks for your Anvil API key. See Before you connect for where to find it.
No. Add only the URL. Do not add an Authorization header or an API key to the client config. The server signs you in with OAuth: the login page asks for your Anvil API key. If the config has such a header, remove it: some clients then send that header instead of the login token, and every call fails with 401.
The login stores them encrypted in the authorization grant of your connection. The server uses them to call the Anvil API for you and to derive a private account id for usage metering. usefulapi does not show them on any page or in any reply. To stop all access, remove the connector and change or delete these credentials in Anvil.
Yes, if you approve it. 4 of the 10 Anvil tools can create or change data. The other 6 are marked read-only. Most MCP clients ask you to approve a tool call before it runs.
The Free plan gives 50 tool calls / month. Pro costs $9/mo or $90/yr, with 10,000 tool calls / month. Pro+ costs $39/mo or $390/yr, with 100,000 tool calls / month. Each subscription covers this Anvil server only. Cancel any time: your paid plan then runs to the end of the paid period. Run anvil_usage_status to see how many calls you used.
Ask the AI to run anvil_upgrade and choose Pro or Pro+, billed monthly or yearly: it returns a Stripe Checkout link. If you already have Pro, ask to change it to Pro+. After you confirm, your existing subscription changes in place, keeps its billing interval and charges the price difference for the rest of the period immediately. To cancel, run anvil_cancel_subscription. Your paid plan continues to the end of the paid period.
Tell the AI what you wanted to do. It can send the request with anvil_request_feature. We store the text with the server name, the type of AI client and the tool you tried, not with your account, and read every request when we plan new tools. You can send up to 5 requests per day.
Any client that supports remote MCP servers (Streamable HTTP) with OAuth login: Claude (web and desktop), Claude Code, ChatGPT, Codex, Cursor, VS Code, Windsurf and others.
This is a Model Context Protocol endpoint — meant to be connected from an AI client, not opened in a browser. An invalid_token response at the URL is the auth gate working as designed; clients authenticate automatically.
Need a tool this server does not have, or a connection to another system? We build custom integrations and MCP servers.