> For the complete documentation index, see [llms.txt](https://docs.moderncollections.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.moderncollections.io/clients/clients.md).

# Clients and MCP

The Python client, the mc-api CLI, the MCP server for agents, and generating your own client.

One package, `mc_api`, ships three front-ends over a single hardened HTTP client, so the library, the CLI and your agent tools all take the same code path:

| Front-end                | What it is                                     |
| ------------------------ | ---------------------------------------------- |
| `mc_api.client.MCClient` | A typed, synchronous Python client.            |
| `mc-api`                 | A CLI covering the same surface.               |
| `mc-api-mcp`             | An MCP stdio server exposing the API as tools. |

{% hint style="warning" %}
**Not on PyPI.** There is no `mc-api` or `moderncollections` package on the public index — do not install lookalikes. The package is distributed by Modern Collections during onboarding; the import name is `mc_api`.
{% endhint %}

```bash
pip install ./mc_api        # path to the provided package
```

There is **no JavaScript SDK** today and no `@moderncollections/*` package on npm. Use `fetch`, `axios` or `undici` against the REST API, or [generate a client](#generate-your-own-client).

## Configuration

All three front-ends read the same environment variables. Configuration never comes from command-line arguments or tool arguments, so your key stays out of shell history and MCP client config that may be logged.

| Variable          | Value                                                                                                                       |
| ----------------- | --------------------------------------------------------------------------------------------------------------------------- |
| `MC_API_ENV`      | `demo` or `prod`                                                                                                            |
| `MC_API_BASE_URL` | An explicit base URL — overrides `MC_API_ENV`                                                                               |
| `MC_API_KEY`      | `ca_<prefix>_<secret>` or `pa_<prefix>_<secret>`                                                                            |
| `MC_API_CREDITOR` | Which linked creditor a **partner** key acts on — a creditor UUID or its `external_creditor_ref`. Ignored for a `ca_…` key. |

**There is no production default.** A target must be selected explicitly, so a forgotten flag can never silently aim a test key at production. The CLI also accepts `--env` / `--base-url` as global options before the subcommand.

The key travels only in the `Authorization` header. It is never logged or printed, excluded from `repr()` output, and tool and CLI errors carry only the API's opaque `detail` and HTTP status.

## CLI

```bash
export MC_API_ENV=prod
export MC_API_KEY="ca_a3f8c0d1_..."

mc-api health
mc-api placements list --status in_outreach
mc-api placements create --company-name "Acme Inc." --invoice-amount 7500.00 --state TX
mc-api placements get <placement-id>
mc-api payments record <placement-id> --amount 2500.00 --idempotency-key pay-2026-08-03-01
mc-api disputes list --status open
```

The command tree mirrors the API surface — placements, payments, disputes, documents, evidence, remittances, statements, exports, settings, notifications, agreements, intake, analytics and the QuickBooks integration. Run `mc-api --help`, or `mc-api <group> --help`, for the current set of commands and flags; that output is generated from the client itself and cannot drift.

Add `--json` for machine-readable output. The CLI exits non-zero on API errors, so it composes in scripts.

Only idempotent `GET`s are auto-retried. `POST /v1/placements` is never auto-retried, by design, so a create cannot be duplicated.

## MCP server

`mc-api-mcp` is a **local stdio process** you run alongside your MCP client — there is no hosted MCP server at a public URL. It registers as `modern-collections` and exposes the creditor-API-key surface as `snake_case` tools — placements, documents and evidence, payments, disputes, remittances and statements, analytics and exports, settings and notifications, agreements, the QuickBooks integration, and intake.

**The server enumerates its own tools.** Point your client at it for the current list rather than working from a count on a documentation page.

### Register it

```json
{
  "mcpServers": {
    "modern-collections": {
      "command": "mc-api-mcp",
      "env": {
        "MC_API_ENV": "prod",
        "MC_API_KEY": "ca_REPLACE_WITH_YOUR_CREDITOR_KEY"
      }
    }
  }
}
```

An `mcp.example.json` template ships in the package. With Claude Code:

```bash
claude mcp add modern-collections -- mc-api-mcp
```

### The `creditor` parameter

A `ca_…` key is scoped to one creditor, so every call runs against it. A **partner** key is not — each call has to name the creditor it acts for. Every tool therefore accepts one extra optional parameter, `creditor`: a creditor UUID or the link's `external_creditor_ref`, defaulting to `MC_API_CREDITOR` and sent as the `X-MC-Creditor` header. It is ignored on a creditor key.

Set `MC_API_CREDITOR` when a server process works a single creditor; pass `creditor` per call to override it. That is how one server works across several of a partner's creditors:

```
placement_list(status="in_outreach", creditor="acme-freight")
placement_improve(placement_id="<uuid>", creditor="northwind-supply")
```

A partner key naming no creditor fails `400 X-MC-Creditor header required`; one naming a creditor with no active link fails `404 Creditor not found`.

### Tools that have real-world effects

{% hint style="warning" %}
These start **real debtor outreach**: `placement_create`, `intake_csv_commit`, `intake_file_confirm`, `intake_draft_resolve` (action `approve`), `intake_structured_submit`.

These are binding or destructive: `agreement_accept` (legally binding), `dispute_resolve`, `qbo_disconnect`, `intake_webhook_rotate_secret` (invalidates the previous secret), `notification_settings_replace` (replaces the whole grid).

Call any of them **only on an explicit instruction**, never to explore the API.
{% endhint %}

Two further notes. `POST /v1/settings/api-key/rotate` has no tool — it is gated on a dashboard session by design, so a leaked key cannot mint its own replacement. And two tools return binary payloads (`settings_agent_skills`, `agreement_certificate`), so they write to a local path and return that path rather than inlining bytes.

`document_upload` reads from local disk only when `MC_API_MCP_UPLOAD_ROOT` names a directory of user-approved documents; it otherwise takes `content_base64`.

### A worked loop

```
improve_overview()
→ ranks active placements by how much attention their file needs

placement_improve(placement_id="<uuid>")
→ { missing_documents: [ { document_type: "signed_delivery_receipt",
      where_to_look: "your dispatch system",
      search_hints: ["INV-4411", "Acme Freight", "7500.00"] } ], ... }

document_upload(file_path="~/ap/acme/POD-4411.pdf", placement_id="<uuid>",
                document_type="signed_delivery_receipt")
document_process(document_id="<doc-uuid>")

placement_improve(placement_id="<uuid>")
→ { evidence: { score: 78, grade: "B" }, missing_documents: [] }
```

## Generate your own client

The [OpenAPI 3.1 spec](https://github.com/knollmeyersam-dot/MC-Docs/tree/main/api-reference/rest-api/openapi.yaml) ships with these docs and is generated directly from the live application schema, so request and response shapes are field-accurate by construction.

```bash
openapi-generator-cli generate -i api-reference/rest-api/openapi.yaml -g typescript-fetch -o ./mc-client
# or
oapi-codegen -package mc api-reference/rest-api/openapi.yaml > client.go
```

{% hint style="info" %}
Always generate from the shipped `openapi.yaml`. It is curated and pruned to the supported external contract; the server's raw `/openapi.json` is not curated for codegen and is not a supported integration surface.
{% endhint %}

Regenerate whenever the spec version changes — it is regenerated whenever the API changes.

## See also

* [Quickstart](/getting-started/quickstart.md)
* [REST API](/rest-api/conventions.md)
* [Platform partners](/rest-api/partner-model.md)


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