OpenTools by Fulin Labs
One balance for the tools your agent calls.
Open OpenTools by Fulin Labs →- Category
- Developer Tools
- Pricing
- Pay per call
- Platform
- Web, API, MCP, CLI
- Last updated
A developer can give an AI agent access to outside tools and APIs with one key and a spending limit, instead of opening an account with each provider. The agent sees the price before a run, and a run is billed only when the provider returns a result.
OpenTools by Fulin Labs is a tool broker for AI agents. An agent finds a tool in the catalog, reads its price and input schema, runs it, and the cost comes out of one prepaid balance.
What problem does OpenTools solve?
An agent that calls ten third-party APIs usually needs ten accounts, ten keys and ten bills. OpenTools puts one integration in front of them: the agent talks to OpenTools, and OpenTools talks to the provider.
How does OpenTools work?
The loop has four steps: discover, inspect, run, poll. Discover is a plain-language search over the catalog. Inspect returns the exact input schema and the price. Run executes the endpoint, either inline or as an async run that the agent polls. A daily budget and a per-call cap can stop a run before it executes, and a run is billed only when the provider delivers a result.
You can connect an agent through a Skill, through the remote MCP server at /mcp, or with the opentools command line tool. The catalog includes listings the studio owner runs, such as BudgetAtlas lodging price data and read-only Polymarket market data.
Who is OpenTools for?
Developers who build or use AI agents and want them to call outside tools with a spending limit, a visible price and one bill.
Try it
New workspaces start with $1 in free credit: opentools-three.vercel.app
Part of Fulin Labs. See the full lineup of projects.
Key features
- Search the tool catalog in plain language, read the input schema and price, then run the endpoint
- Pay per call from one prepaid balance, with no API key for each provider
- Connect an agent through a Skill, a remote MCP server or the opentools command line
- A daily budget and a per-call cap can block a run before it starts
- A run is billed only when the provider returns a result
FAQ
What is OpenTools?
OpenTools is a broker between an AI agent and the tools it calls. The agent searches a catalog, reads an endpoint's schema and price, runs it, and pays from one prepaid workspace balance.
How much does OpenTools cost?
Each endpoint shows the provider's own rate, and OpenTools adds a 10% service fee on top, shown before every run. There are no subscriptions or minimums. A new workspace starts with $1 in free credit.
Which agents can use OpenTools?
The site lists Claude Code, Cursor, Codex and Cline, and any client that supports MCP. A Skill file and a command line tool are also available.
Do I need an API key from every tool provider?
No. The agent holds one OpenTools key, and OpenTools handles the call to the provider.
One balance for the tools your agent calls.
Open OpenTools by Fulin Labs →