MCP Character Tools

The last thing you need for your LLM to work with individual characters or count the number of r's in a word. This is an MCP server providing 14+ comprehensive (and pretty) character and text analysis tools to help LLMs work with individual characters - something they struggle with due to tokenization.

See the Difference

Why This Exists

First of all, why not? Second, Large Language Models tokenize text into subwords, not individual characters. For example, "strawberry" might become tokens like ["straw", "berry"], so the model never truly "sees" individual letters. This MCP server gives LLMs "character-level vision" through a suite of tools.

Installation

Via npx (recommended)

npx mcp-character-tools

Via npm (global install)

npm install -g mcp-character-tools
mcp-character-tools

From source

git clone https://github.com/Aaryan-Kapoor/mcp-character-tools
cd mcp-character-tools
npm install
npm run build
npm start

Usage with Claude Desktop

Add to your Claude Desktop configuration (claude_desktop_config.json):

{
  "mcpServers": {
    "char-tools": {
      "command": "npx",
      "args": ["mcp-character-tools"]
    }
  }
}

All Tools Reference

See sample_outputs.md for complete examples with inputs and outputs for all 14+ tools.

Tool	Description
count_letter	Count a specific letter
count_letters	Count multiple letters at once
count_substring	Count substring occurrences
letter_frequency	Get frequency distribution
spell_word	Break into characters
char_at	Get character at index
nth_character	Get nth character (1-based)
word_length	Get exact length
reverse_text	Reverse text, detect palindromes
compare_texts	Compare two texts
analyze_sentence	Word-by-word breakdown
batch_count	Count across multiple words
get_tricky_words	List commonly miscounted words
check_tricky_word	Check if word is tricky

Development

# Install dependencies
npm install

# Build
npm run build

# Run tests
npm test

# Run tests with coverage
npm run test:coverage

# Development mode with auto-rebuild
npm run dev

Testing

The project includes comprehensive tests for all tools:

npm test

Test files:

• tests/counting.test.ts - Counting tools tests
• tests/spelling.test.ts - Spelling tools tests
• tests/analysis.test.ts - Analysis tools tests
• tests/tricky-words.test.ts - Tricky words resource tests
• tests/visualization.test.ts - Visualization utility tests

License

MIT