OneTool MCP Server

🧿 One MCP for developers - No tool tax, no context rot.
100+ tools including Brave, Google, Context7, Excalidraw, Version Checker, Excel, File Ops, Database, Image Vision, Playwright & Chrome DevTools Utils and many more.

Works with Claude Code or any MCP client

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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:

__run 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. 30× lower cost. No context rot.

📖 Read the full story

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Install

Requires uv:

uv tool install 'onetool-mcp[all]'   # everything
onetool init --config ~/.onetool

Add to Claude Code:

claude mcp add onetool -- onetool serve --config ~/.onetool/onetool.yaml --secrets ~/.onetool/secrets.yaml

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

{
  "mcpServers": {
    "onetool": {
      "command": "onetool",
      "args": ["serve", "--config", "/Users/yourname/.onetool/onetool.yaml", "--secrets", "/Users/yourname/.onetool/secrets.yaml"]
    }
  }
}

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

Verify: onetool init validate --config ~/.onetool/onetool.yaml

📖 Full installation guide

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Use from the CLI

Works as an MCP server and as a direct CLI bridge into a running MCP process. Useful for agent harnesses, scripts, and automation:

# Recommended local MCP root mode: stdio
onetool serve --config .onetool/onetool.yaml

# URL-based MCP root mode for containerized clients
onetool serve --transport http --config .onetool/onetool.yaml --host 127.0.0.1 --port 8767 --path /mcp

# Enable the MCP-owned direct API in onetool.yaml:
# direct.host.enabled: true

# Start OneTool as MCP, then use the port printed in startup logs.
onetool direct run --port 8765 "ot.packs()" --format json | jq '.[0].name'
onetool direct run --port 8765 "brave.search(query='latest AI news')" --format raw

📖 Direct usage 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 — __run brave.search(q="AI")
Live Whiteboard	Draw diagrams with a Mermaid-compatible DSL via Excalidraw
MCP Server Proxy	Wrap existing MCP servers without the tool tax
Encrypted Secrets	age-encrypted secrets.yaml backed by your OS keychain
Forge Tools	Build new tools as part of the conversation
Image Vision	Routes to a cheaper, better vision model via ot_image (img). Zero host tokens. Supports local files, URLs, clipboard; PNG, JPEG, GIF, WebP, TIFF, HEIC, AVIF, SVG.
Smart Context	ot_context (ctx) — SQLite+FTS5 store. Search and navigate large outputs without filling the context window.
Caveman Compact	ot_caveman (cm) — LLM-powered text compaction. 55–65% on tech prose, 25–31% on search results, 45–55% on conversational prose. __compact__ = True applies it to any tool call. Code blocks, URLs, and security warnings are never modified.
Smart Tools	Delegate to cheaper LLMs (10× savings)
Security Layers	AST validation, path boundaries, output sanitisation

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Tools

27+ packs, 230+ tools ready to use:

Pack	Tools	Extra	Description
brave	search, news	[util]	Web and news search
chrome_util	highlight_element, guide_user	[dev]	Browser annotations (DevTools)
context7	search, doc	[dev]	Library documentation
convert	pdf_to_md, docx_to_md, pptx_to_md	[util]	Document conversion
db	query, schema, tables, sample	[dev]	Database operations
diagram	create, get_playground_url	[dev]	Mermaid / Kroki diagrams
excel	read, write, query	[util]	Excel files
file	read, write, grep, slice, toc	[util]	File operations
ground	search	[util]	Google Grounding search
knowledge	search, ask, write, read, grep	[util]	RAG knowledge base (FTS5+vector)
mem	write, read, search, grep, ask, inspect, query	[util]	Persistent memory
ot_forge	create_ext, validate_ext, install_skills		Scaffold new tool packs
ot_context (ctx)	write, read, search, grep, slice, toc		Smart context store (SQLite+FTS5)
ot_caveman (cm)	compact, expand, input		LLM-powered text compaction and expansion
ot_image (img)	load, load_batch, ask, summary, list, delete, purge	[util]	Image vision via dedicated model
ot_llm	transform, transform_file		LLM-powered transforms
ot_secrets	init, encrypt, audit, rotate		Secrets encryption
ot_timer	start, elapsed, list		Named timers
ot	help, tools, stats, skills		Introspection
package	npm, pypi, cargo	[dev]	Package versions
play_util	highlight_element, guide_user	[dev]	Browser annotations (Playwright)
ripgrep	search, count	[dev]	Fast code search
tavily	search, search_batch, research	[util]	AI-native search
webfetch	fetch, fetch_batch	[dev]	Web fetching
whiteboard	open, draw, screenshot, save	[dev]	Live Excalidraw canvas

📖 Complete tools reference — full summary table with all 230+ tools

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MCP Server Proxy

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

# .onetool/onetool.yaml
servers:
  local_tools:
    type: stdio
    command: npx
    args: ["-y", "some-mcp-server@latest"]
  private_api:
    type: http
    url: ${PRIVATE_MCP_URL}
    auth:
      type: bearer
      token: ${PRIVATE_MCP_TOKEN}

__run private_api.read_resource(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")

__run 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
• Dev Docs - Internal developer documentation
• Specifications - OpenSpec specifications index

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References

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

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Telemetry

OneTool sends anonymous startup pings (event type, version, OS). No personal data. Opt out: export DO_NOT_TRACK=1 or set telemetry.enabled: false in onetool.yaml. Details

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Issues

Check for existing issues first:

• Browse the tracker: github.com/beycom/onetool-mcp/issues
• Search with GitHub syntax: is:issue repo:beycom/onetool-mcp <keyword>

Raise a new issue: github.com/beycom/onetool-mcp/issues/new

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Support

If you find OneTool useful:

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License

GPLv3