OpenAI (and Anthropic) gave agents a way to describe tool calls. You still have to write every tool. MeterCall gives you 2,400 tools pre-wired, metered, and payable per call.
Function calling is a protocol — a schema format and a calling convention. MeterCall is a catalog — 2,400 real endpoints that speak that protocol. You need both.
Protocol baked into the Chat Completions and Responses APIs. You define a JSON schema, the model calls it, you execute. BYO tools — you still write the Stripe adapter, the Salesforce adapter, the Twilio adapter...
Catalog of 2,400 wired modules. Agent calls POST /v1/stripe/charges. We meter, we bill, we hand the response back. Pair with OpenAI function calling by returning the MeterCall endpoint as the tool.
| OpenAI Function Calling | MeterCall | |
|---|---|---|
| What it is | Protocol — schema + calling convention | Catalog + runtime — 2,400 actual tools |
| Tools included | Zero. You build each one. | 2,400 production-wired, ready to call. |
| Billing | Upstream billing is your problem per tool | One meter. $0.001/call. One invoice. |
| Agent-pay | No native agent-wallet support | Yes — x402 live, agent pays per call |
| Model lock-in | OpenAI-specific shape (Responses API) | Framework-agnostic — works with GPT, Claude, Gemini, any model |
| Best fit | Use function calling as the protocol. Use MeterCall as the backend each tool routes into. | |
Register MeterCall modules as OpenAI functions. Each function's body is one HTTPS call to MeterCall. Your agent gets 2,400 tools without you writing 2,400 adapters — and you get a single bill.
Beta is open. $0.001 per call. 2,400 tools wired to OpenAI function calling.
Join the Beta See all comparisons