brex

Brex through One

Brex combines corporate cards, business accounts, expense management, bill pay, and travel booking into a single AI-powered financial operations platform—offering unified spend control, real-time visibility, automated workflows, and modern treasury tools designed for startups and enterprises across 120+ countries.

One exposes Brex through four MCP tools. The table below carries real action ids from One's knowledge base, so for a common operation you can skip search and go straight to reading the action's parameters.

How to run an action

1. Find the action in the table below, or call search_one_platform_actions with platform brex if it is not listed.
2. Call get_one_action_knowledge with the action id. Do this every time, including for actions in this table. The table gives you the id, not the parameters.
3. Call execute_one_action with parameters copied from that knowledge.

Never guess a parameter name, a body field, or an enum value. The knowledge has the real schema, and a guessed field is either a 400 or a silent write of the wrong thing.

Before you start

Call list_one_integrations once and confirm Brex is connected. If it is missing, the user has not connected it: say so and point them at https://app.withone.ai rather than reaching for raw HTTP.

Each connection carries an access field. If it reports {"policy": "methods", "methods": ["GET"]} the agent is read-only here, so plan a read-only answer instead of attempting a write that will be refused.

Before a write

Creates, updates, deletes and sends land on a real Brex account and cannot be recalled. State the action and the specific target in one line before the first write in a task, and let the user stop you. Reads need no confirmation.

Actions

Budgets

Action	Method	Path	Action id
Get a Budget by ID	GET	/v2/budgets/{{id}}	conn_mod_def::GJ094hSR8nE::Z4He1qh-SfGiP8JuXyLXww
Get a Spend Limit by ID	GET	/v1/budgets/{{id}}	conn_mod_def::GJ09-jcQaTU::ZmKtsfSmQOyi8XzCA4luzw
List Budgets	GET	/v2/budgets	conn_mod_def::GJ094q6dtMY::1uQwvjk6R928D49LMnzCrw
List Spend Limits	GET	/v1/budgets	conn_mod_def::GJ09-qOKmWE::oFeeoTxJQku6eUilAEGYQA
Archive a Budget	POST	/v2/budgets/{{id}}/archive	conn_mod_def::GJ094RIHbtQ::VnWj4-OmSYewvpL6Uur_8w
Archive a Spend Limit	POST	/v1/budgets/{{id}}/archive	conn_mod_def::GJ09-SSCsRM::atiUQpjvTFSlLRcGfzVBBA
Create a Spend Limit	POST	/v1/budgets	conn_mod_def::GJ09-aEiULY::G5M1llCBTEm4DWpYPpI49A
Create Budget	POST	/v2/budgets	conn_mod_def::GJ094Z8EAKM::_MF_lncnRcO0Fr2Cuor5jA
Update a Budget	PUT	/v2/budgets/{{id}}	conn_mod_def::GJ094y8cYgw::OrUQReSGQqyXexDH-ie8iQ
Update a Spend Limit	PUT	/v1/budgets/{{id}}	conn_mod_def::GJ09-yXPMqU::LYPOEFUoSzy6snCkEFLzTw