String Utility Belt — Claude Code MCP server: how to install
MCP server providing 247 string utilities and pipeline execution directly to AI agents. Runs locally without a browser.
claude mcp add mcp -- npx -y @string-utility-belt/mcpWhat String Utility Belt does
The server exposes 247 text transformation utilities and a pipeline engine directly to the AI agent. Tools include list_utilities for catalog lookups, describe_utility for checking parameters, and run_utility alongside run_pipeline for running single or multi-step operations. An extra tool, detect_format, inspects unrecognized formats such as JWT or YAML.
Executions run inside pooled child processes — up to 4 workers capped at 512 MB memory each. Every request has a 20-second timeout, while text input cannot exceed 1 MB. Running arbitrary JavaScript through custom_js is blocked completely. Tools needing a browser DOMParser, like xml_to_json and html_table_to_csv, will return errors.
The package requires Node.js 20 or newer. All processing happens in local machine memory without sending network requests to external servers.
What it helps with
- decode Base64 payloads and format resulting JSON structures
- identify unknown data formats such as JWT or YAML
- chain multi-step text transformations through structured pipelines
- convert binary hex encodings into raw text output
Example prompts for the agent
- Decode this base64 string and pretty-print the resulting JSON with subelt tools.
- Run detect_format on this token string to check what format it uses.
- Build a pipeline to strip whitespace and normalize line endings.
How to install String Utility Belt
Platform CLI
claude mcp add mcp -- npx -y @string-utility-belt/mcpPlatform CLI
codex mcp add mcp -- npx -y @string-utility-belt/mcpConfig file
{
"mcpServers": {
"mcp": {
"command": "npx",
"args": [
"-y",
"@string-utility-belt/mcp"
]
}
}
}Config file
{
"servers": {
"mcp": {
"type": "stdio",
"command": "npx",
"args": [
"-y",
"@string-utility-belt/mcp"
]
}
}
}Platform CLI
gemini mcp add mcp npx -y @string-utility-belt/mcpStep by step, with commands for each platform: How to add an MCP server to Claude Code, Codex, Cursor, VS Code, Gemini CLI and more
Questions about String Utility Belt
How to install String Utility Belt in Claude Code?
Run claude mcp add mcp -- npx -y @string-utility-belt/mcp in your terminal. You must have Node.js 20 or later installed.
What does String Utility Belt do?
It equips your AI assistant with 247 text transformation tools and a pipeline engine. The assistant looks up utilities through list_utilities and executes them locally in isolated child processes.
What execution limits does the server enforce?
Input text cannot exceed 1 MB per call, and executions timeout after 20 seconds. Outputs larger than 1M characters get truncated, while arbitrary JavaScript execution remains blocked.
