Guide · API vs. MCP
API and MCP.
Two doors to the same account.
An API connects systems: your code decides every call. MCP connects AI assistants to the same data: the agent discovers the tools and picks one to answer a question. This guide shows the difference in practice, with the same question answered both ways.
Short answer
In 30 seconds.
The difference is who writes the call.
- APIFor systems you program
A list of addresses, the endpoints, with fixed rules. A developer writes every call in code, with the exact fields, and the same input has the same effect. It's how you automate: issue charges, pay batches, feed the ERP.
- MCPFor AI assistants that converse
An open standard that connects assistants such as Claude to outside systems. The MCP server describes the tools it offers; the agent reads those descriptions and decides which one to call to answer a plain-language question. It's how you look things up and analyze them.
- At TrioThe same data both ways
Every Trio MCP tool mirrors a read endpoint of the Trio API: the agent sees the same documents, statuses and identifiers as your integration. Trio MCP is read-only; payments go out through the API or the app, under the account's approval rules.
1.0 API
An API is the exact order.
Every field in place, every time.
Think of a purchase order: the form has fixed fields, and the supplier only accepts it when everything is filled in the agreed way. An API (Application Programming Interface) works like that. It publishes addresses, called endpoints, and the format of each request. Your system sends the request, the API answers, and the result is predictable.
- ContractThe format is public and fixedThe Trio API is described in OpenAPI, the standard that defines HTTP interfaces so that people and machines understand a service without reading its code.
- Who decidesThe developer writes every callWhich endpoint, in what order, with which filters and what to do with the answer: it all lives in the integration's code, written and tested in advance.
- ResultPredictable and repeatableThe same request has the same effect. That's why the API is the way to run operations at volume, such as paying 2,400 suppliers or issuing 10,000 boletos a month.
- ExampleA Pix through the Trio APIPOST /v2/out/pix/async with the source account (bank_account_id), the amount in cents and the recipient. The response carries the new document, and a webhook tells you when the Pix settles.
2.0 MCP
MCP is AI's universal port.
One plug, many assistants.
The Model Context Protocol is an open standard, launched by Anthropic in November 2024 and now housed at the Agentic AI Foundation, part of the Linux Foundation. MCP's own documentation compares it to USB-C: just as one standard port connects different devices, MCP connects AI assistants to outside data and tools without a custom integration for every pair.
- HostThe assistant you useThe AI application, such as Claude. It opens one MCP client for each server it connects to.
- ServerThe system that offers the toolsA program that exposes tools, data and prompt templates. Trio MCP is a server hosted by Trio.
- tools/listThe agent asks what existsOn connecting, the client asks for the list of tools. Each comes with a name, a description of when to use it and the shape of its arguments.
- tools/callThe agent picks and callsGiven a question, the model picks the tool that answers it, fills in the arguments and reads the result. The agent writes the call, on the spot.
3.0 In practice
The same question,
two paths.
"How much did we pay Vértice Engenharia in September?" Through the API, someone writes the code that fetches, walks the pages and adds up, and the answer shows on a dashboard. Through MCP, a person asks the assistant, and the agent calls Trio MCP's tools. The number is the same, because the source is the same.
- APIBest when the question repeatsIt becomes a report, a dashboard or an automation: the code runs every month, the same way.
- MCPBest when the question is newOne-off analysis and checks before approving, without waiting for a new report.
4.0 Why MCP exists
From 20 connections to 9.
AI's travel adapter.
Without a standard, every AI assistant needs its own integration with every system: 4 assistants and 5 systems make 20 custom integrations. With a common protocol, each side plugs into the standard once: 4 + 5 = 9. That's the problem Anthropic named when it launched MCP: every new data source required its own implementation.
- No standard4 × 5 = 20Custom integrationsEvery assistant and system pair has its own code, its own authentication and its own upkeep.
- With MCP4 + 5 = 9Connections to the standardEach system publishes an MCP server once, and any compatible assistant can use it.
- And the API?It stays underneathAn MCP server usually calls an API behind the scenes. MCP doesn't replace the API: it makes it usable by agents.
5.0 Side by side
The full comparison.
Point by point.
The differences that matter when you choose, with what applies at Trio specifically.
| Aspect | API | MCP |
|---|---|---|
| Who uses it | Systems and developers | AI assistants and the people talking to them |
| Who writes the call | The code, written in advance | The agent, on the spot, from the question |
| How you find out what exists | Reading the docs (OpenAPI) | The server lists its tools (tools/list) |
| Format | HTTP with JSON, one endpoint per operation | JSON-RPC 2.0, tools with a description and an argument schema |
| Access at Trio | Integration credentials (HTTP Basic) | The person signs in through the browser, with access limited to the organization |
| Predictability | High: same input, same effect | The agent may take different paths; check the answer |
| What it does at Trio | Read and write: payments, billing, accounts | Read-only: balances, statements, payments, collections and cards |
| To get started | Build and test in the Sandbox | Add Trio MCP to the assistant and sign in with your user |
| Best for | Automation at volume and repeated processes | One-off questions, analysis and checks |
6.0 Security
Agents read, analyze and explain.
People approve.
Giving an agent access doesn't mean handing over the keys to the vault. The MCP standard itself recommends least privilege: access starts with only what's needed. Trio MCP takes that all the way, and no tool moves money. When a payment has to go out, it goes through the API or the app and follows the account's approval rules.
- Trio MCPRead-onlyNo tool creates payments, transfers or refunds, issues cards or changes settings.
- Trio MCPOne organization per accessEvery call runs with the session's credentials and sees only that organization's data. Card numbers and CPFs arrive masked.
- APIIntegration credentialsWhoever writes through the API uses their own credentials, kept on the company's servers and never in the browser.
- AccountApproval rules always applyPayments follow the approval rules by amount and by CNPJ set on the account.
7.0 When to use each
Choose by the job,
not the hype.
Four common situations in finance and the path that solves each. Pick one to see the route.
Frequently asked
questions.
Does MCP replace the API?
No. MCP is a layer for AI agents, and an MCP server usually calls an API behind the scenes. At Trio, every Trio MCP tool mirrors a read endpoint of the API. Integrations that automate payments and billing stay on the API.
Do I need to code to use Trio MCP?
No. Add Trio MCP to a compatible assistant, such as Claude, and sign in with your Trio user. The API takes an integration to build, and the Sandbox lets you test without real money.
Can the agent make payments through Trio MCP?
No. Every Trio MCP tool is read-only: none creates payments, transfers or refunds. An agent that executes payments has to be built on the API, with its own credentials, and its payments follow the account's approval rules.
Is it safe to connect an AI assistant to the company account?
Trio MCP follows least privilege: read-only, access limited to one organization, and card numbers and CPFs masked. Each person signs in with their own user, and the agent sees only what that organization sees. More in Security.
Which assistants work with Trio MCP?
Claude and other MCP-compatible clients. The step-by-step setup is in the Trio MCP documentation.
Do the agent's numbers match the integration's?
Yes, because the source is the same: the tools use the API's documents, statuses and identifiers. Still, check the numbers before you decide, as you would with any analysis.