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tech.unravel/mcp-vegalite-server

tech.unravel/mcp-vegalite-server

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github.com/unravel-teamData & Analytics1Updated 79w ago
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About tech.unravel/mcp-vegalite-server

An MCP server for preparing data and rendering Vega-Lite visualizations with `vl-convert`. It provides a simple two-step flow for hosts that generate visualization specifications with an LLM.

Key features

  1. 01Save data for visualization
  2. 02Render Vega-Lite specifications
  3. 03Use `vl-convert` for rendering

Use cases

  1. 01Turn prepared data into Vega-Lite charts
  2. 02Render LLM-generated visualization specifications

MCP support

Exposes `save-data` and `visualize-data` tools to MCP clients, supporting data storage and rendering of Vega-Lite specifications.

Configuration

Local server config is the same for every client. Copy it into your client’s MCP config file.

mcp.json · Universal config
{
  "mcpServers": {
    "vegalite-server-unravel-team": {
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/inspector"
      ]
    }
  }
}
Run commandnpx -y @modelcontextprotocol/inspector

Local servers need a runtime on your machine (e.g. Node.js 18+). Config file locations differ by client; see your client’s docs.

Packages
npm@modelcontextprotocol/inspector

Tools

No tool list yet

Local servers expose tools only once running on your machine, and the maintainer has not provided a tool list.

Details

From the project README

tech.unravel/mcp-vegalite-server

An MCP server for working with Vegalite, using vl-convert.

We create two simple tools:

  • save-data
  • visualize-data

Using these, a host can create beautiful vegalite diagrams by:

  • calculating the data needed and saving it,
  • then generating the vegalite-spec using an LLM
  • then rendering the spec using the data and access to vl-convert

Usage

Building the Jar
$ make clean && make build
Running the MCP server

PRE-REQUISITES: Needs vl-convert CLI to be installed.

Some example commands you can try in Claude Desktop or Inspector:

Here is some example data for you:

[
    { "year": 2011, "value": 14.6, "growth_type": "Market Cap Growth" },
    { "year": 2011, "value": 11.4, "growth_type": "Revenue Growth" },
    { "year": 2011, "value": 26.6, "growth_type": "Net Income Growth" },
    { "year": 2012, "value": 40.1, "growth_type": "Market Cap Growth" },
    { "year": 2012, "value": 42.7, "growth_type": "Revenue Growth" },
    { "year": 2012, "value": 36.9, "growth_type": "Net Income Growth" },
    { "year": 2013, "value": 16.9, "growth_type": "Market Cap Growth" },
    { "year": 2013, "value": 14.6, "growth_type": "Revenue Growth" },
    { "year": 2013, "value": 15.3, "growth_type": "Net Income Growth" },
    { "year": 2014, "value": 9.6, "growth_type": "Market Cap Growth" },
    { "year": 2014, "value": 7.9, "growth_type": "Revenue Growth" },
    { "year": 2014, "value": 10.9, "growth_type": "Net Income Growth" },
    { "year": 2015, "value": 5.8, "growth_type": "Market Cap Growth" },
    { "year": 2015, "value": 6.7, "growth_type": "Revenue Growth" },
    { "year": 2015, "value": 6.2, "growth_type": "Net Income Growth" },
    { "year": 2016, "value": -12.4, "growth_type": "Market Cap Growth" },
    { "year": 2016, "value": -3.9, "growth_type": "Revenue Growth" },
    { "year": 2016, "value": -32.2, "growth_type": "Net Income Growth" },
    { "year": 2017, "value": 25.3, "growth_type": "Market Cap Growth" },
    { "year": 2017, "value": 5.9, "growth_type": "Revenue Growth" },
    { "year": 2017, "value": 43.9, "growth_type": "Net Income Growth" }
]

Visualize this data for me using vega-lite.

Before running the vegalite MCP server

Remember:

  1. Replace the full-path to the mcp-vegalite-server JAR with the correct path on your system
  2. Specify the full-path to vl-convert on your system
In Claude Desktop
    "vegalite": {
      "command": "java",
      "args": [
        "-Dclojure.tools.logging.factory=clojure.tools.logging.impl/log4j2-factory",
        "-Dorg.eclipse.jetty.util.log.class=org.eclipse.jetty.util.log.Slf4jLog",
        "-Dlog4j2.contextSelector=org.apache.logging.log4j.core.async.AsyncLoggerContextSelector",
        "-Dlog4j2.configurationFile=log4j2-mcp.xml",
        "-Dbabashka.json.provider=metosin/jsonista",
        "-Dlogging.level=INFO",
        "-Dmcp.vegalite.vl_convert_executable=/Users/vedang/.cargo/bin/vl-convert",
        "-cp",
        "/Users/vedang/mcp-vegalite-server/target/tech.unravel/mcp-vegalite-server-1.0.0.jar",
        "tech.unravel.mcp_vegalite_server"
      ]
    }
In MCP Inspector

Remember to use the full-path to the mcp-vegalite-server JAR on your system.

npx @modelcontextprotocol/inspector java -Dclojure.tools.logging.factory=clojure.tools.logging.impl/log4j2-factory -Dorg.eclipse.jetty.util.log.class=org.eclipse.jetty.util.log.Slf4jLog -Dlog4j2.contextSelector=org.apache.logging.log4j.core.async.AsyncLoggerContextSelector -Dlog4j2.configurationFile=log4j2-mcp.xml -Dbabashka.json.provider=metosin/jsonista -Dlogging.level=INFO -Dmcp.vegalite.vl_convert_executable=/Users/vedang/.cargo/bin/vl-convert -cp /Users/vedang/mcp-vegalite-server/target/tech.unravel/mcp-vegalite-server-1.0.0.jar tech.unravel.mcp_vegalite_server

License

Copyright © 2025 Unravel.tech Engineering

Distributed under the MIT License

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