How to Use the ISS Calculator MCP in Claude

Get accurate Brazilian service tax (ISS) answers directly inside Claude Desktop. No more searching government websites.

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Connect ISS Calculator MCP to Claude Desktop

Create your Vinkius account to connect ISS Calculator to Claude Desktop — we handle the hosting, security, and runtime updates so you don't have to. No server setup required.

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Setup ISS Calculator with Claude Desktop

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Find Correct Tax Rates Instantly

Ask Claude for the tax rate for any service in any Brazilian municipality. It uses the `get_applicable_rate` tool to give you the exact percentage. Whether you're using the native desktop app or claude.ai, you just ask in plain English. This MCP connects directly to the relevant tax data, so you get a straight answer without digging through PDFs.

Clarify Withholding Rules

Some services require you to withhold ISS at the source. Instead of guessing, just ask your agent to `check_withholding_status` for a specific service and city combination. This is perfect for a quick sanity check before issuing an invoice or making a payment. You get a simple yes or no, which avoids costly mistakes and compliance headaches.

Calculate Final Tax Bills in Chat

Once you have the rate and withholding status, you can have Claude `calculate_tax_liability` on any invoice amount. It handles the math for you. This turns a multi-step research process into a simple conversation. You can connect this remote MCP to your claude.ai account in seconds and start getting answers.

Setup guide

Set up ISS Calculator MCP in Claude Web or Desktop

1

Open Claude Settings

Go to claude.ai, click your profile icon, then navigate to Customize → Connectors.
2

Add Custom Connector

Click the "+" button and select Add custom connector. Paste your Vinkius endpoint URL: https://edge.vinkius.com/[YOUR_TOKEN_HERE]/mcp Replace [YOUR_TOKEN_HERE] with your token from cloud.vinkius.com. For OAuth-protected servers, expand Advanced settings to add credentials.
3

Start a conversation

Open a new chat. The ISS Calculator MCP tools are available immediately — no restart needed.

Endpoint URL

https://edge.vinkius.com/[YOUR_TOKEN_HERE]/mcp

No configuration file needed — paste the URL directly in the Claude web interface.

Available on Free (1 connector), Pro, Max, Team, and Enterprise plans.

Prerequisites

Claude Desktop installed (macOS or Windows)
Active Vinkius subscription with a valid endpoint token

1

Open Claude Desktop Settings

Click the menu icon at the top-left corner, go to Settings → Developer → Edit Config. This opens claude_desktop_config.json in your default text editor.
2

Paste the ISS Calculator MCP configuration

Copy the JSON snippet on the right into the mcpServers object. Replace [YOUR_TOKEN_HERE] with your endpoint token from cloud.vinkius.com.
3

Restart Claude Desktop

Close and reopen the application. Claude needs a full restart to load new MCPs — refreshing a conversation is not enough.
4

Verify the connection

Open a new conversation. Click the 🔌 icon at the bottom of the message input. You should see tools listed under iss-calculator-mcp.

json

{
  "mcpServers": {
    "iss-calculator-mcp": {
      "url": "https://edge.vinkius.com/[YOUR_TOKEN_HERE]/mcp"
    }
  }
}

Get your connection token →

Independent Platform Disclaimer: Vinkius is an independent platform and is not affiliated with, endorsed by, sponsored by, verified by, or otherwise authorized by ISS Calculator. All third-party trademarks, logos, and brand names are the property of their respective owners. Their use on this website is strictly for informational purposes to identify service compatibility and interoperability.

Why Choose Vinkius

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Common questions about ISS Calculator MCP in Claude Desktop

Install it from the Extensions menu in the Claude Desktop app for local use, or add the MCP URL as a Custom Connector on claude.ai. Then, just ask questions about ISS tax rates and calculations in your chat.

Yes. Provide the service type and municipality, and the ISS Calculator will find the correct tax rate. It's much faster than looking up municipal codes yourself.

It covers all municipalities that have their ISS tax data available. If a city's data is published, this tool can access it for you.

The local desktop install runs the MCP as a process on your machine, which is good for offline access or development. The web connector points to a managed Vinkius MCP and requires zero installation.

Yes. The tool only processes non-sensitive data like municipality names, service codes, and invoice amounts. All communication with the remote MCP is encrypted in transit, and Vinkius never stores your query history.

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