# bexio-mcp-server MCP Server

Swiss accounting integration for Bexio. 314 tools: invoices, contacts, projects, account balances

**Publisher claimed.** No tool list reported, and Pod has not connected to this server.

## Status

Pod has not dialled bexio-mcp-server yet, so everything on this page is what its publisher reported rather than what we observed. Registries describe servers; they do not connect to them. Until a check runs, treat the tool list below as a claim.

## Connect

Published as `@promptpartner/bexio-mcp-server` on npm. Runs locally.

## Known issues

**15 problems reported by people outside the maintainer team.** Issues filed by the project's own owners, members and collaborators are excluded — those are release checklists and internal refactors, not things that will go wrong for you. Showing 12.

### Most discussed

### Orphaned server processes busy-loop at ~100% CPU after client disconnect (stdio)

## Summary
When the MCP client disconnects (window close / session restart) without a graceful
shutdown, the `bexio-mcp-server` process does **not exit**. Instead it appears to
busy-loop and pins a full CPU core at ~100%. Orphaned instances accumulate over a
work session, each spinning — three were running simultaneously here (~300% CPU
total) while completely idle (no requests).

## Environment
- `@promptpartner/bexio-mcp-server` **2.4.0** (latest on npm)
- Launched via `npx` over **stdio** by 

[Read the thread](https://github.com/PromptPartner/bexio-mcp-server/issues/11) · 2026-06-19 · closed · external user · 2 comments

### create_bill / create_outgoing_payment: misleading description and undocumented required fields

## Summary
`create_bill` and `create_outgoing_payment` accept an open `additionalProperties` object whose required structure is undocumented, and `create_bill`'s description is actively misleading. Creating a single bill + payment took ~10 trial-and-error round trips driven only by the API's validation errors.

## Environment
- **v2.3.0** (unchanged in v2.4.0)

## `create_bill`
Description says: *"Bill data including contact_id, title, positions, etc."*
Reality (v4 `purchase/bills`):
- `contact_

[Read the thread](https://github.com/PromptPartner/bexio-mcp-server/issues/9) · 2026-06-16 · closed · external user · 2 comments

### All write tool parameters received as `undefined` — write operations don't work

## Bug Report

All create/update/delete tools fail because the server receives every parameter as `undefined`, 
even when explicitly provided by the Claude client. Read-only tools with no required parameters 
(e.g. `list_invoices`) work fine.

## Steps to Reproduce

Call `create_contact` with the following parameters:
- `contact_type`: `"company"`
- `name_1`: `"Test GmbH"`

## Expected Behavior

Contact is created successfully in Bexio.

## Actual Behavior
```json
{
  "code": "VALIDATION_ERROR",

[Read the thread](https://github.com/PromptPartner/bexio-mcp-server/issues/2) · 2026-03-13 · closed · external user · 2 comments

### create_iban_payment produces a standalone payment with no bill link (silently breaks bill reconciliation)

## Summary
`create_iban_payment` creates a **standalone banking payment that is not linked to any bill** (`bill_id` is always `null`). When an agent or user reaches for it to pay a supplier bill — the obvious-sounding choice for "an IBAN payment" — the result silently breaks the normal accounting workflow: the bill stays in status **"Offen"**, its **Zahlungen** section stays empty, and **automatic bank reconciliation can never match the payment to the bill**. Nothing in the tool description warn

[Read the thread](https://github.com/PromptPartner/bexio-mcp-server/issues/12) · 2026-06-19 · closed · external user · 1 comment

### download_file returns entire file as inline base64, overflowing client context

## Summary
`download_file` returns the entire file as an inline base64 string inside the JSON tool result. For anything but tiny files this overflows the MCP client's context window. A 226 KB PDF produced a ~308,000-character result that the client refused to load.

## Environment
- **v2.3.0** (unchanged in v2.4.0)

## Root cause
`src/bexio-client.ts`:
```ts
async downloadFile(fileId) {
  const response = await axios.get(`.../3.0/files/${fileId}/download`, { responseType: "arraybuffer", ... });

[Read the thread](https://github.com/PromptPartner/bexio-mcp-server/issues/10) · 2026-06-16 · closed · external user · 1 comment

### Most recent

### upload_file always fails with HTTP 415 — Bexio's POST /3.0/files requires a bare Accept: application/json header

## Summary

`upload_file` fails for every input with `INTERNAL_ERROR: Request failed with status code 415`. It is not size- or content-related: a 4-byte file fails exactly like a 484 KB PDF.

Root cause: Bexio's `POST /3.0/files` validates the `Accept` header strictly and only accepts the exact value `application/json`. `BexioClient.uploadFile()` sets only the multipart headers from `form-data` plus `Authorization`, so axios' default `Accept: application/json, text/plain, */*` goes out — and Bex

[Read the thread](https://github.com/PromptPartner/bexio-mcp-server/issues/20) · 2026-07-28 · open · external user · 0 comments

### `edit_invoice` always fails: `PUT /kb_invoice/{id}` is not a valid Bexio 2.0 route (edit is `POST`), and the merged payload includes fields the edit form rejects

Every call to the `edit_invoice` tool fails with:

```
Bexio API error: The form could not be saved due to the following errors:.
```

regardless of the payload. Three separate problems combine here — the first one is the blocker,
the other two made it undiagnosable / will make it fail again once the first is fixed:

### 1. Wrong HTTP method (blocker)

`editInvoice` sends `PUT /kb_invoice/{id}`, but the Bexio **2.0** API has no PUT route for
`kb_invoice` — the edit operation is `POST /2.0/kb_inv

[Read the thread](https://github.com/PromptPartner/bexio-mcp-server/issues/19) · 2026-07-18 · open · external user · 0 comments

### #11 regression: EPIPE feedback loop in global uncaughtException handler — orphaned stdio server spins at 100% CPU again (v2.4.1)

## Summary

The #11 fix (exit on stdin end/close) works for a *clean* disconnect, but the global `uncaughtException` handler added in v2.4.0 (index.ts, "log, do NOT exit") re-introduces the 100%-CPU orphan through a different path: once stderr's pipe/socket peer is gone, every `logger.error()` call throws `EPIPE`, which lands in the `uncaughtException` handler, which logs it via `logger.error()` to the same dead stderr → next `EPIPE` → self-sustaining loop (~1000 exceptions/sec, one CPU core pin

[Read the thread](https://github.com/PromptPartner/bexio-mcp-server/issues/18) · 2026-07-08 · open · external user · 0 comments

### create_contact / bulk_create_contacts: advertised `address` field is rejected by Bexio (empty 422) — writable fields are street_name / house_number

## Observed (2026-07-03, live company, latest npx build)

Creating a contact with the `address` field the tool schema advertises (`src/tools/contacts/definitions.ts:186`, and `:252` in the bulk variant — `address: { type: "string", description: "Street address" }`) is rejected by Bexio with a **422 whose error list is empty**, which makes the failure very hard to diagnose from the tool result. It cost our agent three failed calls before it found the working shape.

What Bexio actually accepts fo

[Read the thread](https://github.com/PromptPartner/bexio-mcp-server/issues/17) · 2026-07-03 · open · external user · 0 comments

### upload_file: accept a local file path (symmetric to download_file's output_path)

## Context

We drive this server from an agent (Claude Code) that registers receipt PDFs as purchase-bill attachments. Real-world PDFs are hundreds of KB to several MB.

## Problem

`upload_file` accepts file content only as inline base64 (`src/tools/files/handlers.ts:45-47` — params go straight to `client.uploadFile`). Through an LLM tool call that is impractical and corruption-prone: the base64 blob has to pass through the model's context (token cost, hard size ceiling, and any re-tokenization

[Read the thread](https://github.com/PromptPartner/bexio-mcp-server/issues/16) · 2026-07-03 · open · external user · 0 comments

### Optional receipt-gating for irreversible writes (payments / issue·cancel·send invoice / deletes) — one file, zero deps, off by default

Hi — really nice project; the planning docs, tests, and the standalone-payment warning on `create_iban_payment` show you take the dangerous surface seriously. That's exactly why I'm raising this.

A handful of your tools take **irreversible, money-touching actions** that an agent can trigger with no record that an accountable human approved *that specific action*:

- `create_iban_payment`, `create_qr_payment`, `create_outgoing_payment` — move real money
- `issue_invoice`, `cancel_invoice`, `send

[Read the thread](https://github.com/PromptPartner/bexio-mcp-server/issues/15) · 2026-06-30 · open · external user · 0 comments

### Bills (kb_bill) endpoints use v2.0 API instead of v4.0

## Problem

The purchase bill endpoints (`list_bills`, `get_bill`, `create_bill`, `search_bills`, etc.) all return **404 Not Found** because they use the v2.0 API base URL (`https://api.bexio.com/2.0/kb_bill`).

Bexio has moved the bills API to **v4.0** at `https://api.bexio.com/4.0/purchase/bills`.

## Affected code

In `bexio-client.js`, all bill methods use the v2.0 base URL:

```js
async listBills(params = {}) {
    return this.makeRequest("GET", "/kb_bill", params);  // 404 on v2.0
}
```

#

[Read the thread](https://github.com/PromptPartner/bexio-mcp-server/issues/1) · 2026-02-18 · closed · external user · 1 comment

[See all 15 reports Pod holds for bexio-mcp-server](/mcp/bexio-mcp-server/issues).

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