OneTool MCP

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The Problem

Each MCP server consumes 3K-30K tokens per request. Connect 5 servers and you've burned 55K tokens before the conversation starts. Connect 10+ and you're at 100K tokens.

The math is brutal: Claude Opus 4.5 at $5/M input tokens, 20 days × 10 conversations × 10 messages × 3K tokens = $30/month per MCP server - even if you never use the tools.

And then there's context rot - your AI literally gets dumber as you add more tools (Chroma Research, 2025).

The Solution

OneTool is one MCP server that exposes tools as a Python API. Instead of reading tool definitions, your agent writes code:

__ot brave.search(query="react docs 2026")

Configure one MCP server. Use unlimited tools.

"Agents scale better by writing code to call tools instead. This reduces the token usage from 150,000 tokens to 2,000 tokens...a cost saving of 98.7%"

— Anthropic Engineering

96% fewer tokens. 24× lower cost. No context rot.

📖 Read the full story

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See It In Action

Demo	Description
Compare the Search	Side-by-side token comparison
Build a Wikipedia Tool	Create a custom tool in seconds

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Install

Requires uv:

uv tool install onetool-mcp
onetool init

Add to Claude Code:

claude mcp add onetool onetool

Or manually add to ~/.claude/mcp.json:

{
  "mcpServers": {
    "onetool": {
      "command": "onetool"
    }
  }
}

That's it. All 100+ tools work out of the box.

Verify: onetool init validate

📖 Full installation guide

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Features

Feature	Description
96% Token Savings	~2K tokens no matter how many tools you add
100+ Built-in Tools	Web search, databases, file ops, diagrams, conversions
Explicit Execution	See exactly what runs - __ot brave.search(q="AI")
MCP Server Proxy	Wrap existing MCP servers without the tool tax
Scaffold Tools	Build new tools as part of the conversation
Smart Tools	Delegate to cheaper LLMs (10× savings)
Single YAML Config	Global configuration, per-pack settings, includes
Security Layers	AST validation, path boundaries, output sanitisation

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Tools

15 packs, 100+ tools ready to use:

Pack	Tools	Description
brave	search, news	Web and news search
context7	resolve, get_docs	Library documentation
convert	pdf_to_md, docx_to_md, pptx_to_md	Document conversion
db	query, schema, tables	Database operations
diagram	create	Mermaid diagrams
excel	read, write, query	Excel files
file	read, write, list, search	File operations
ground	search	Google Grounding
llm	transform, transform_file	LLM-powered transforms
ot	help, tools, stats	Introspection
package	npm, pypi, cargo	Package versions
ripgrep	search, count	Fast code search
scaffold	tool	Generate new tools
web	fetch, fetch_batch	Web fetching

📖 Complete tools reference — full summary table with all 100+ tools

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MCP Server Proxy

Wrap any existing MCP server and call it explicitly - without the tool tax:

# .onetool/onetool.yaml
mcp_servers:
  chrome-devtools:
    command: npx
    args: ["-y", "@anthropic-ai/chrome-devtools-mcp@latest"]
  github:
    command: npx
    args: ["-y", "@anthropic-ai/github-mcp-server@latest"]

__ot mcp.call(server="github", tool="get_file_contents", arguments={"path": "README.md"})

📖 Configuration guide

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Extending

Drop a Python file, get a pack. No registration, no config:

# .onetool/tools/wiki.py
pack = "wiki"

def summary(*, title: str) -> str:
    """Get Wikipedia article summary."""
    import httpx
    url = f"https://en.wikipedia.org/api/rest_v1/page/summary/{title}"
    return httpx.get(url).json().get("extract", "Not found")

__ot wiki.summary(title="Python_(programming_language)")

📖 Creating tools guide

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Documentation

• Quickstart - 30 seconds to first tool call
• Installation - All platforms
• Configuration - YAML schema
• Tools Reference - All 100+ tools
• Security - Security layers
• Extending - Build your own

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References

• Code Execution with MCP - Anthropic Engineering
• Context Rot - Chroma Research

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License

GPLv3 - Will transition to MIT at v2.0.

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Support

If you find OneTool useful: