Eraser

You can use the Eraser MCP Server to create diagrams on Eraser.io directly from your MCP client. It validates diagram syntax, fixes common issues, and returns direct links to view and edit your diagrams, all through a Docker-based integration with Claude Desktop.

How to use

You use an MCP client to send a diagram in Eraser DSL to the Eraser MCP Server. The server can create diagrams of types such as sequence diagrams, flowcharts, cloud architecture diagrams, and entity-relationship diagrams. You can also validate syntax before creation and let the server automatically fix common mistakes.

How to install

Prerequisites you need before starting:

1. Get an Eraser API key from your Eraser.io account settings.

2. Build the Docker image used for Claude Desktop integration with the following commands:

git clone <repository-url>
cd eraser-mcp
./scripts/build-claude-docker.sh

3. Configure Claude Desktop to run the MCP server via Docker. Create or update your Claude Desktop settings with the following configuration file content:

{
  "mcpServers": {
    "eraser": {
      "command": "docker",
      "args": [
        "run",
        "-i",
        "--rm",
        "-e", "ERASER_API_KEY=yourapikey",
        "eraser-mcp:claude"
      ]
    }
  }
}

4. After saving the configuration file, completely quit and restart Claude Desktop.

5. Test the integration by asking Claude Desktop to perform common tasks such as creating a sequence diagram or validating a diagram syntax.

6. Optional: Create a Claude Desktop project to organize diagram syntax references and provide persistent access to your knowledge base.

• Create a new project in Claude Desktop by clicking the "+" icon in the sidebar.

• Name your project (for example, “Eraser Diagrams” or “System Architecture”).

• Add the syntax guide by uploading or copying diagram syntax documentation to your project knowledge base.

With the setup complete, you can chat with Claude using the Eraser MCP tools to create, validate, and fix diagrams with full knowledge of the proper syntax for all supported diagram types.

Configuration and usage details

The Eraser MCP Server exposes a small set of tools you can call from your MCP client. You can create diagrams, validate syntax, and automatically fix common errors.

Available tools include:

• create_diagram: Creates a new diagram on Eraser.io and returns direct view and edit links.

• validate_diagram: Validates Eraser diagram syntax and returns any errors.

• fix_diagram: Validates and fixes common syntax issues and returns the fixed content.

Examples

Creating a Sequence Diagram example content:

Client > Server: Request
Server > Database: Query
Database --> Server: Results
Server --> Client: Response

Creating a Flowchart example content:

Start [shape: oval]
Start > Process
Process > Decision [shape: diamond]
Decision > End [shape: oval]

Validation and automatic fixes

The server performs validation for all supported diagram types and automatically applies common fixes, such as correcting arrow syntax, adding missing brackets or quotes, trimming trailing whitespace, and ensuring proper shape names.

Troubleshooting

Docker image not found or misconfigured: ensure you have built the docker image correctly and that the container name and tag match the configuration.

API key issues: verify that your API key is correct in the configuration and that it is accessible to the running container.

Permission issues: make sure Docker is running and your user has permission to run Docker commands.

Development

If you are developing or extending the MCP server integration, you can use the included Dev Container setup.

Open the project in a compatible editor and follow the steps to modify code and rebuild the image as needed.

Diagram syntax documentation

For detailed syntax guidance, refer to the syntax references for Sequence Diagrams, Flowcharts, Entity Relationship Diagrams, and Cloud Infrastructure diagrams.

Available tools

create_diagram

Creates a new diagram on Eraser.io and returns direct links to view and edit it.

validate_diagram

Validates Eraser diagram syntax and reports any errors or warnings.

fix_diagram

Validates and automatically fixes common syntax errors in Eraser diagrams and returns the fixed content.