Using OpenClaw for real world invoicing via REST tools

I wanted to test OpenClaw beyond text tasks and see how stable it is with transactional workflows.

So I connected it to an invoicing API backend and exposed structured REST endpoints as tools.

Setup:

• Strict JSON schema for invoice creation

• Endpoints for create, fetch, update, overdue filter

• Server side validation on every request

• No middleware automation layer

Example input:

“Create invoice for Acme Corp, 40 hours at 120 per hour”

The agent maps:

• client

• line items

• quantity

• rate

• totals

Then performs a POST request to the API.

What I observed:

1. Schema strictness matters more than prompt tuning.

2. If optional fields are loosely defined, the agent invents values.

3. Financial workflows require server side validation even if the agent behaves correctly.

4. Tool response formatting affects future reasoning quality.

The interesting part is how reliably OpenClaw handles structured financial actions when the schema is tight.

Curious how others are handling:

• Stateful financial workflows

• Error recovery after failed tool calls

• Preventing duplicate transactional actions

• Idempotency design with agents

Would like to compare approaches.