# Equation.io

Turns equations into interactive 2D and 3D graphs and returns a link that carries the whole graph state. Handy when a formula needs a picture in the reply.

- MCP server · `type=mcp` · Claude Code, Codex, Cursor, GitHub Copilot, Windsurf (Devin Desktop), Cline, Zed, Gemini CLI · ★ 408
- Author: aantthony
- License: MIT · policy=link-only · description only; the file stays with the author
- Source: https://github.com/aantthony/equation.io
- Updated: 2026-10-24
- HTML: https://affpapa.org/en/nevibecode/mcp/equationio

## What it does

The server takes equations, validates the rows and hands back a link to the interactive grapher. Three tools do the work: `encode_graph_url` builds a link from equations, `decode_graph_url` parses an existing link back into editable rows, and `show_graph` renders the grapher inside MCP Apps hosts. Graph state lives in the URL as `/g/eq1;eq2`, so the address bar is the share mechanism.

The math runs on the site. Expressions compile to GLSL shaders: 2D curves are drawn in a fragment shader, and 3D surfaces appear automatically once `z` shows up in an equation. The server is stateless over Streamable HTTP, so there is nothing to run locally — just the endpoint `https://equation.io/mcp`.

These tools are built for an agent rather than a person at a calculator. You can drop the link into a reply, and `show_graph` will display the graph where the host supports MCP Apps. Everywhere else you get the link and a PNG preview.

## Requirements
- Remote server: `https://equation.io/mcp`

## Install

### Claude Code (native platform)

**Platform CLI: remote server**
```bash
claude mcp add --transport http equation https://equation.io/mcp
```

### Codex

**Platform CLI: remote server**
```bash
codex mcp add equationio --url https://equation.io/mcp
```

### Cursor

**Config file**
File `.cursor/mcp.json`:
```json
{
    "mcpServers": {
        "equationio": {
            "url": "https://equation.io/mcp"
        }
    }
}
```

### GitHub Copilot

**Config file**
File `.vscode/mcp.json`:
```json
{
    "servers": {
        "equationio": {
            "type": "http",
            "url": "https://equation.io/mcp"
        }
    }
}
```

### Gemini CLI

**Platform CLI: remote server**
```bash
gemini mcp add -t http equationio https://equation.io/mcp
```

## When to use it
- build a shareable link to an interactive graph from a set of equations
- validate equations before rendering and surface a clear error
- decode someone else's graph link back into equations for editing
- show a 3D surface from a formula inside an agent reply
- deliver a graph as an image where interactivity is not supported

## Example prompts
- Graph `y = x^2` and give me the link
- Make a link to the 3D surface `z = sin(x)cos(y)`
- Decode this graph link and show me the equations

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