
Agent Toolbelt MCP
- 1 repo stars
- Updated August 4, 2026
- marras0914/agent-toolbelt
Agent Toolbelt MCP is an MCP server that exposes 19 hosted agent utilities—including contract review, prompt optimization, and context packing—via stdio and an API key.
About
Agent Toolbelt MCP wraps a suite of nineteen small, opinionated APIs behind one stdio Model Context Protocol server so developers do not hand-roll HTTP clients for every agent helper. Typical uses land in agent-tooling: compressing context before a long thread, tuning prompts before a codegen pass, or running contract-style checks on interfaces the agent just drafted. Registration uses npm identifier agent-toolbelt-mcp with an AGENT_TOOLBELT_KEY environment variable, which keeps setup to a key and an npx-style launch path. The value is breadth—many discrete tools in one catalog entry—rather than deep domain replacement for your database or deploy stack. Pair it when you want lightweight LLM workflow utilities on demand inside Claude Code or Cursor without maintaining nineteen separate integrations.
- 19 focused HTTP-backed tools exposed through one MCP server
- Includes contract review, prompt optimizer, and context packing
- stdio npm package agent-toolbelt-mcp (registry version 1.0.1)
- Requires AGENT_TOOLBELT_KEY; free key at documented Railway signup URL
- GitHub source under marras0914/agent-toolbelt mcp-server subfolder
Agent Toolbelt MCP by the numbers
- Data as of Aug 10, 2026 (Skillselion catalog sync)
claude mcp add --env AGENT_TOOLBELT_KEY=YOUR_AGENT_TOOLBELT_KEY agent-toolbelt-mcp -- npx -y agent-toolbelt-mcpAdd your badge
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| repo stars | ★ 1 |
|---|---|
| Package | agent-toolbelt-mcp |
| Transport | STDIO |
| Auth | Required |
| Last updated | August 4, 2026 |
| Repository | marras0914/agent-toolbelt ↗ |
What it does
Attach 19 hosted Agent Toolbelt APIs—contract review, prompt optimization, context packing, and more—to your agent via stdio MCP.
Who is it for?
Best when you want a pre-built utility belt for prompts, context, and contract checks without building micro-APIs yourself.
Skip if: Skip if you need only local offline tools, strict air-gapped environments, or a single-purpose integration with no cloud API.
What you get
After you set AGENT_TOOLBELT_KEY and add the stdio server, the agent can invoke all 19 Toolbelt APIs as named MCP tools during implementation.
- 19 callable MCP tools backed by Agent Toolbelt APIs
- Faster prompt and context workflows without custom HTTP glue
By the numbers
- 19 focused API tools per server description
- MCP package version 1.0.0; npm package version 1.0.1
- Transport: stdio via agent-toolbelt-mcp on npm
README.md
Agent Toolbelt
Stock research tools for AI agents. Live financial data + Claude-synthesized analysis, served as 7 focused tools — not raw OHLCV. Plus 20 utility tools for the rest of an agent's work.
Production API: https://www.agenttoolbelt.live
Quickstart
# Get a free API key (1,000 calls/month, no credit card)
curl -X POST 'https://www.agenttoolbelt.live/api/clients/register' \
-H "Content-Type: application/json" \
-d '{"email": "you@example.com"}'
# Generate a Motley Fool-style investment thesis for any ticker
curl -X POST https://www.agenttoolbelt.live/api/tools/stock-thesis \
-H "Authorization: Bearer atb_YOUR_KEY" \
-H "Content-Type: application/json" \
-d '{"ticker": "NVDA", "timeHorizon": "3-5 years"}'
Returns: bullish/neutral/bearish verdict, thesis paragraphs, key strengths, key risks, valuation read, insider read, analyst consensus read, and what to watch in the next earnings report.
Stock research tools (7)
LLM-synthesized analysis on top of live financial data from Polygon.io, Finnhub, and Financial Modeling Prep.
| Tool | What it does | Price |
|---|---|---|
stock-thesis |
Full Motley Fool-style investment thesis: verdict + thesis paragraphs + strengths + risks + valuation read | $0.05/call |
earnings-analysis |
EPS beat/miss history, revenue trend, long-term earnings consistency read, upcoming earnings date | $0.05/call |
insider-signal |
Form 4 interpretation — distinguishes meaningful open-market purchases from routine sales/awards. Signal strength + confidence | $0.05/call |
valuation-snapshot |
P/E, P/S, EV/EBITDA, FCF yield, ROE, margins → cheap/fair/expensive verdict + specific buy zone | $0.05/call |
bear-vs-bull |
Steelmanned 3-bull / 3-bear case with specific data, net verdict, key debate question | $0.05/call |
compare-stocks |
Head-to-head comparison of 2-3 tickers. Winner + per-ticker strengths/concerns + ifYouValue map (growth / value / quality) | $0.05/call |
moat-analysis |
Buffett-style competitive moat assessment (brand / switching costs / network / scale / IP / cost). Wide/narrow/none + durability | $0.05/call |
Every stock tool returns a dataSources block with fetchedAt + per-source success flags so you know exactly what data backed the analysis.
Utility tools (20)
Common agent infrastructure. Rule-based tools billed at $0.0001–$0.001/call; LLM-powered tools at $0.005–$0.10/call.
| Tool | What it does | Price |
|---|---|---|
text-extractor |
Extract emails, URLs, phones, dates, currencies, addresses, names from text | $0.0005/call |
token-counter |
Count tokens across 15 LLM models with cost estimates | $0.0001/call |
schema-generator |
JSON Schema / TypeScript / Zod validator from plain English | $0.001/call |
csv-to-json |
CSV to typed JSON with auto delimiter and type casting | $0.0005/call |
markdown-converter |
HTML ↔ Markdown conversion | $0.0005/call |
url-metadata |
Title, OG tags, favicon, author from any URL | $0.001/call |
web-summarizer |
Fetch + summarize a URL with key points | $0.02/call |
regex-builder |
Natural language → regex with JS/Python/TS snippets | $0.0005/call |
cron-builder |
Schedule description → cron expression with next-run preview | $0.0005/call |
address-normalizer |
US address → USPS format with component parsing | $0.0005/call |
color-palette |
Color palettes with WCAG scores and CSS vars | $0.0005/call |
brand-kit |
Full brand kit — colors, typography, CSS/Tailwind tokens | $0.001/call |
image-metadata-stripper |
Strip EXIF/GPS/IPTC/XMP metadata for privacy | $0.001/call |
meeting-action-items |
Action items, decisions, summary from meeting notes | $0.05/call |
prompt-optimizer |
Score and rewrite LLM prompts | $0.05/call |
document-comparator |
Semantic diff between two document versions | $0.05/call |
contract-clause-extractor |
Key clauses + risk flags from contracts | $0.10/call |
api-response-mocker |
Realistic mock data from a JSON Schema | $0.0005/call |
dependency-auditor |
CVE scan for npm/PyPI packages via OSV database | $0.005/call |
context-window-packer |
Pack content into a token budget for LLM context | $0.001/call |
Do you know what your agent is actually calling?
You wired up the tools. Once the agent is running, though, you have no visibility into which ones it calls or what it passes to them. I also built Cordon for this. It sits in front of any MCP server and logs every call. You can write rules to block the ones you don't want touching production.
getcordon.com — npx @getcordon/cli init
npm SDK + LangChain
npm install agent-toolbelt
Typed client
import { AgentToolbelt } from "agent-toolbelt";
const client = new AgentToolbelt({ apiKey: process.env.AGENT_TOOLBELT_KEY! });
// Stock research
const thesis = await client.stockThesis({ ticker: "NVDA", timeHorizon: "3-5 years" });
const moat = await client.moatAnalysis({ ticker: "AAPL" });
const compare = await client.compareStocks({ tickers: ["NVDA", "AMD"] });
// Utility
const tokens = await client.tokenCounter({ text: myDocument });
const contacts = await client.textExtractor({
text: emailBody,
extractors: ["emails", "phone_numbers", "addresses"],
});
LangChain integration
import { AgentToolbelt } from "agent-toolbelt";
import { createLangChainTools } from "agent-toolbelt/langchain";
import { createReactAgent } from "@langchain/langgraph/prebuilt";
import { ChatOpenAI } from "@langchain/openai";
const client = new AgentToolbelt({ apiKey: process.env.AGENT_TOOLBELT_KEY! });
const tools = createLangChainTools(client); // 27 ready-to-use DynamicStructuredTools
const agent = createReactAgent({
llm: new ChatOpenAI({ model: "gpt-4o" }),
tools,
});
Claude MCP
Use the stock research tools (and the rest of the toolbelt) directly inside Claude Desktop or Claude Code via the agent-toolbelt-mcp package.
Claude Desktop — add to claude_desktop_config.json:
{
"mcpServers": {
"agent-toolbelt": {
"command": "npx",
"args": ["-y", "agent-toolbelt-mcp"],
"env": {
"AGENT_TOOLBELT_KEY": "atb_your_key_here"
}
}
}
}
Claude Code — one command:
claude mcp add agent-toolbelt -e AGENT_TOOLBELT_KEY=atb_your_key_here -- npx -y agent-toolbelt-mcp
Once installed, ask Claude things like "Give me a full analysis of NVDA — thesis, earnings quality, insider activity, and whether it's cheap right now" and it'll call the tools in parallel.
Discover tools programmatically
Agents can auto-discover all 27 tools at runtime:
curl https://www.agenttoolbelt.live/api/tools/catalog
Pricing
| Tier | Price | Monthly calls | Rate limit |
|---|---|---|---|
| Free | $0/mo | 1,000 | 10/min |
| PAYG | prepaid credits | unlimited | 60/min |
| Starter | $29/mo | 50,000 | 60/min |
| Pro | $99/mo | 500,000 | 300/min |
| Enterprise | Custom | 5,000,000 | 1,000/min |
Integrations
- npm SDK —
npm install agent-toolbelt— typed client + LangChain tools - MCP —
npx -y agent-toolbelt-mcp— works with Claude Desktop and Claude Code - OpenAI GPT Actions — OpenAPI spec at
/openapi/openapi-gpt-actions.json - RapidAPI — listed on the RapidAPI marketplace
- Smithery, Glama, PulseMCP, MCP registry — discoverable in MCP directories
Going to production
When the agent moves out of dev, a new set of questions shows up. What did it call last night? What arguments did it pass? Who approved the destructive one?
Cordon is an MCP gateway that sits in front of servers like this one. Point your client at Cordon instead of directly at Agent Toolbelt; Cordon forwards every call through and adds:
- A real-time audit log of every tool invocation (name, arguments, response, latency)
- Per-API-key policy: which tools each caller can use, under what conditions
- Slack-based human approvals for tool calls you've flagged as high-risk
From the agent's perspective nothing changes — same tools, same schemas. Free tier covers 1,000 events/month.
License
MIT
Recommended MCP Servers
How it compares
Bundled cloud API MCP with 19 tools, not a self-hosted security gateway like Cordon.
FAQ
Who is Agent Toolbelt MCP for?
Developers and agent-heavy developers who want nineteen ready-made LLM helper APIs behind one MCP server and one API key.
When should I use Agent Toolbelt MCP?
Use it while building agent features or long coding sessions when you need context packing, prompt optimization, or contract review as explicit tool calls.
How do I add Agent Toolbelt MCP to my agent?
Register the npm stdio server agent-toolbelt-mcp, set AGENT_TOOLBELT_KEY from the free signup at https://agent-toolbelt-production.up.railway.app, and restart your MCP client.