csvbox-mcp-server

A universal Model Context Protocol (MCP) server for CSVBox. It exposes CSVBox importer-sheet management as MCP tools so you can create, replace, patch, generate, validate, and scaffold importers from any MCP-compatible client — Claude Desktop, Cursor, Windsurf, Roo Code, Cline, VS Code, ChatGPT MCP, and more.

Runs over stdio, so it works the same way in every client.

Tools

CSVBox currently has no GET or LIST endpoints, so there are intentionally no get_sheet / list_sheet tools.

It also exposes two MCP prompts:

Prompt → sheet generation

generate_sheet_json and create_importer_from_prompt use an LLM to convert a free-form request into a complete CSVBox sheet — title, sheet_columns, destinations, webhooks, security_settings, and steps. Only actual data fields become columns; destinations, webhooks, domains, regions, file-upload and step settings are placed in their proper configuration sections, never turned into columns. There are three tiers:

1. Server LLM — when ANTHROPIC_API_KEY or OPENAI_API_KEY is set, the server calls the LLM directly. Works in MCP Inspector and headless.

2. MCP prompt (create_csvbox_sheet) — when you have no server key, host clients (Cursor, Claude Desktop, Cline) run the generation with their own model, then call validate_schema and create_sheet. Free.

3. None configured — generate_sheet_json returns a structured "no LLM provider configured" error pointing to the MCP prompt, and create_importer_from_prompt does not call the CSVBox API. There is no regex fallback.

Category / module expansion

The generator runs in one of two modes, chosen automatically from the prompt:

• Extraction (default) — the prompt names concrete fields (e.g. "columns name, email, phone"). Only those become columns; nothing is invented.

• Expansion — the prompt names business modules / categories as a list (e.g. "modules for: Company Information, Suppliers, Payroll, Invoice"), asks for a comprehensive/detailed schema, or asks for a column count ("at least 100 columns"). Each named module is expanded into several realistic, prefixed, correctly-typed columns (e.g. Suppliers → supplier_id, supplier_name, supplier_gstin, supplier_email, …). An explicit minimum count is honored and every column_name is globally unique.

Data types and validations are inferred from the field names and any requested types:

Large schemas: the default models (claude-haiku-4-5, gpt-4o-mini) are cheap but produce noticeably better 100+ column schemas when you override with a stronger model via LLM_MODEL (e.g. claude-sonnet-4-6). The output cap is raised to fit big sheets; if a request is still too large the response is flagged TRUNCATED (a distinct result, not a parse error) and the CSVBox API is not called — reduce the column count / modules or use a model with a larger output budget and retry.

Related MCP server: mcp-tabular

Function collections (virtual columns, validation functions, data transforms)

Beyond the six sheet properties, the CSVBox Sheet API accepts three collections whose items carry a js_code string that CSVBox executes during an import:

Inside js_code the csvbox object exposes row, column, virtual, user, import, and environment. The two accessors are not interchangeable — a virtual column is per-row and uses csvbox.row.<name> (a scalar), while a "column"-scoped function sees the whole column via csvbox.column.<name> (an array).

Shared optional fields: scope (column | row; not on virtual columns), run_at (before_validation | after_validation; data transforms only), columns / dynamic_columns, active, dependencies, and _delete (PATCH only).

Authoring them

// generate_sheet_functions  (requires ANTHROPIC_API_KEY or OPENAI_API_KEY)
{
  "prompt": "add a virtual column joining first and last name, and check every email contains an @",
  "sheet": { "title": "Customers", "sheet_columns": [ ... ] }
}

Returns { "virtual_columns": [...], "validation_functions": [...], "source": ..., "validation": {...} }. Collections the request does not imply are omitted, never returned as empty arrays.

This tool does not call the CSVBox API. Read the generated js_code, then apply it yourself with patch_sheet. Pass sheet so the model references real column names and the validator can check those references — CSVBox has no read endpoint, so it must be supplied inline. Without an LLM key, use the csvbox_sheet_functions MCP prompt instead.

PUT vs PATCH — read this before applying

Use patch_sheet to apply generated functions. Validate first with the matching verb:

// validate_schema
{ "sheet": { "data_transforms": [ ... ] }, "mode": "patch" }

mode is create (default), put, or patch. It only affects the function collections — under put an empty array is a hard error rather than a warning, and _delete is rejected outside patch.

Dependencies

An item may load up to 5 third-party scripts:

{ "url": "https://cdn.jsdelivr.net/npm/dayjs@1.11.10/dayjs.min.js",
  "globals": ["dayjs"],
  "integrity": "sha384-..." }

Only cdn.jsdelivr.net, unpkg.com, and cdnjs.cloudflare.com are allowed; https only, .js/.mjs path, no query string, fragment, userinfo, or port.

Security. This server never executes js_code — it is an opaque string here. Generated JavaScript is unreviewed model output, so read it before you PATCH it into a live importer. A dependency without an integrity digest can change under your customers at any time; validate_schema warns when one is missing.

See docs/sheet-functions-example.json for a full payload.

Installation

npm install @csvbox/mcp-server

Or build from source:

git clone <this-repo> csvbox-mcp-server
cd csvbox-mcp-server
npm install
npm run build

This produces dist/index.js — the entrypoint MCP clients launch.

Environment variables

Copy .env.example to .env and fill in your CSVBox credentials:

CSVBOX_API_KEY=your_api_key
CSVBOX_API_SECRET=your_api_secret

CSVBox credentials are only required for the API-backed tools (create_sheet, update_sheet, patch_sheet, create_importer_from_prompt). validate_schema and generate_import_code work without any credentials.

Auth header note: the client sends x-csvbox-api-key and x-csvbox-secret-api-key (matching the CSVBox reference payloads). These are defined as constants in src/services/csvbox-api.ts if your account uses different header names.

LLM provider (for prompt → sheet generation)

generate_sheet_json and create_importer_from_prompt need an LLM. Set one of:

ANTHROPIC_API_KEY=sk-ant-...
OPENAI_API_KEY=sk-...

The provider is auto-detected:

LLM_PROVIDER disambiguates when both keys are present; LLM_MODEL overrides the model for whichever provider is chosen. For large category/module schemas (100+ columns) set LLM_MODEL to a stronger model (e.g. claude-sonnet-4-6) — see Category / module expansion.

MCP Inspector: set the LLM key in the Inspector's environment-variables panel to use the server-LLM path. Inspector has no host LLM of its own, so it can render the create_csvbox_sheet prompt but cannot execute it — for the keyless path use a client with a model (Cursor, Claude Desktop, Cline).

Running locally

# After building:
npm start

# Or run the built file directly:
node dist/index.js

The server speaks MCP over stdio and logs csvbox-mcp-server running on stdio to stderr (stdout is reserved for the protocol).

Client configuration

For a published installation, use the npm package with npx. Set CSVBOX_API_KEY / CSVBOX_API_SECRET in the env block.

Note: The npm package is @csvbox/mcp-server and the executable is csvbox-mcp-server.

Claude Desktop

Add the following to your Claude Desktop MCP configuration:

{
  "mcpServers": {
    "csvbox": {
      "command": "npx",
      "args": [
        "-y",
        "--package=@csvbox/mcp-server",
        "csvbox-mcp-server"
      ],
      "env": {
        "CSVBOX_API_KEY": "your_api_key",
        "CSVBOX_API_SECRET": "your_api_secret"
      }
    }
  }
}

Cursor

Edit ~/.cursor/mcp.json (global) or .cursor/mcp.json (per-project):

{
  "mcpServers": {
    "csvbox": {
      "command": "npx",
      "args": [
        "-y",
        "--package=@csvbox/mcp-server",
        "csvbox-mcp-server"
      ],
      "env": {
        "CSVBOX_API_KEY": "your_api_key",
        "CSVBOX_API_SECRET": "your_api_secret"
      }
    }
  }
}

Windsurf

Edit ~/.codeium/windsurf/mcp_config.json:

{
  "mcpServers": {
    "csvbox": {
      "command": "npx",
      "args": [
        "-y",
        "--package=@csvbox/mcp-server",
        "csvbox-mcp-server"
      ],
      "env": {
        "CSVBOX_API_KEY": "your_api_key",
        "CSVBOX_API_SECRET": "your_api_secret"
      }
    }
  }
}

Roo Code

In the Roo Code MCP settings (mcp_settings.json):

{
  "mcpServers": {
    "csvbox": {
      "command": "npx",
      "args": [
        "-y",
        "--package=@csvbox/mcp-server",
        "csvbox-mcp-server"
      ],
      "env": {
        "CSVBOX_API_KEY": "your_api_key",
        "CSVBOX_API_SECRET": "your_api_secret"
      }
    }
  }
}

Cline

In the Cline MCP settings (cline_mcp_settings.json):

{
  "mcpServers": {
    "csvbox": {
      "command": "npx",
      "args": [
        "-y",
        "--package=@csvbox/mcp-server",
        "csvbox-mcp-server"
      ],
      "env": {
        "CSVBOX_API_KEY": "your_api_key",
        "CSVBOX_API_SECRET": "your_api_secret"
      }
    }
  }
}

VS Code MCP

Add to .vscode/mcp.json (or the global mcp.json):

{
  "servers": {
    "csvbox": {
      "command": "npx",
      "args": [
        "-y",
        "--package=@csvbox/mcp-server",
        "csvbox-mcp-server"
      ],
      "env": {
        "CSVBOX_API_KEY": "your_api_key",
        "CSVBOX_API_SECRET": "your_api_secret"
      }
    }
  }
}

Example tool calls

Generate a complete sheet from a prompt (LLM, no CSVBox API call):

// generate_sheet_json  (requires ANTHROPIC_API_KEY or OPENAI_API_KEY)
{ "prompt": "Create employee importer with name, email, salary, joining date; destination as testapi; allow only xlsx files" }

Returns { "sheet": { "title": ..., "sheet_columns": [...], "destinations": [...], "steps": {...} }, "source": "llm:anthropic:claude-haiku-4-5", "validation": { "valid": true, ... } }. Data fields become columns (salary → currency, joining date → date); the destination and xlsx setting go to destinations / steps, not columns. With no LLM key, returns an error pointing to the create_csvbox_sheet prompt.

Validate a schema before sending it:

// validate_schema
{ "sheet": { "title": "Customers", "sheet_columns": [
  { "column_name": "email", "display_label": "Email", "type": "email" }
] } }

Returns { "valid": true, "errors": [], "warnings": [ ... ] }.

Create a sheet:

// create_sheet
{ "sheet": { "title": "Customer Import", "sheet_columns": [
  { "column_name": "name", "display_label": "Name", "type": "text" },
  { "column_name": "email", "display_label": "Email", "type": "email" }
] } }

Generate + create in one step:

// create_importer_from_prompt  (requires an LLM key + CSVBox credentials)
{ "prompt": "Create customer importer with name, email, phone; allow for example.com" }

Returns { "generated_schema": { ... }, "source": ..., "validation": { ... }, "api_response": { ... } }. Aborts without calling the API if no LLM provider is configured or the generated schema fails validation.

Replace a sheet:

// update_sheet
{ "sheet_license_key": "abc123", "sheet": { "title": "Updated", "sheet_columns": [ ... ] } }

Destructive for any collection you send — see PUT vs PATCH.

Patch a sheet:

// patch_sheet
{ "sheet_license_key": "abc123", "changes": { "title": "New Title" } }

Remove one function without touching the rest:

// patch_sheet
{ "sheet_license_key": "abc123",
  "changes": { "virtual_columns": [ { "column_name": "full_name", "_delete": true } ] } }

Generate integration code:

// generate_import_code
{ "framework": "react" }

Supported column types

text, number, email, date, time, boolean, regex, ip, url, credit_card, phone_number, currency, list, dependent_list, dynamic_list, dependent_dynamic_list, multiselect_list, multiselect_dynamic_list.

Development

npm run build   # compile TypeScript → dist/
npm start       # run the built server
npm run lint    # type-check without emitting
npm test        # compile and run the unit suite (alias: npm run test:unit)

Tests

npm test compiles src/tests/ and runs it with Node's built-in test runner — no test framework, no mocking library.

The suite is hermetic. It never contacts an external host, never reads your ambient CSVBOX_API_* / ANTHROPIC_API_KEY / OPENAI_API_KEY, and never touches a real CSVBox account, so it passes identically whether or not you have credentials configured. HTTP is intercepted at the axios adapter; the LLM is a scripted fake; the one test that needs real request encoding starts an ephemeral listener on 127.0.0.1 and closes it afterwards. Tests that read environment variables set what they need explicitly and restore the previous values.

E2E tests

npm run test:e2e         # run the Playwright suite
npm run test:e2e:report  # open the HTML report from the last run

Specs live in e2e/, configured by playwright.config.ts. Like the unit suite, this suite is hermetic: it starts mock CSVBox and LLM servers on loopback (e2e/support/mock-csvbox-server.ts, e2e/support/mock-llm-server.ts) and drives the real built server (dist/index.js) through MCP Inspector with fake credentials pointed at those mocks — it never contacts a real CSVBox account or LLM provider, and never reads your .env. A separate, zero-credential Inspector instance covers the "missing credentials" error paths. Requires npm run build first (the test:e2e webServer entries build automatically).

Embedding the server

createServer() is exported from the entry module. It registers every tool and prompt and returns the McpServer without attaching a transport, so you can connect it to one of your own:

import { createServer } from "@csvbox/mcp-server";

const server = createServer();
await server.connect(myTransport);

Importing the module does not start anything; the stdio server runs only when dist/index.js is executed directly.

License

MIT