transkribus-mcp-server

# transkribus-mcp-server

[![Tests](https://github.com/lazyants/transkribus-mcp-server/actions/workflows/test.yml/badge.svg)](https://github.com/lazyants/transkribus-mcp-server/actions/workflows/test.yml)

MCP server for the [Transkribus REST API](https://transkribus.eu/). Manage collections, documents, HTR/OCR recognition, models, and more through the Model Context Protocol.

**304 tools by default**, or **306 with Processing v2**, across 23 resource domains, with 9 entry points so you can pick the right server for your MCP client's tool limit.

> **API scope:** This server covers **two** Transkribus APIs:
>
> - the **legacy TrpServer REST API** (`https://transkribus.eu/TrpServer/rest`), session-based — 300 tools;
> - the **Processing API**, OIDC bearer auth via `account.readcoop.eu` — 4 `transkribus_processing_*` tools with the default Metagrapho v1 backend (`https://transkribus.eu/processing/v1`), or 6 with the optional Developer Platform v2 beta (`https://api-staging.transkribus.org/v2`).
>
> v2 requires explicit selection. Its [published OpenAPI](https://api-staging.transkribus.org/v2/openapi.json) names a staging server; production v2 availability has not been confirmed. Both backends take `config.textRecognition.htrId`.

## Installation

```bash
npm install -g @lazyants/transkribus-mcp-server
```

Or run directly:

```bash
npx @lazyants/transkribus-mcp-server
```

## Configuration

Transkribus uses session-based authentication. Credentials are resolved in this
order, per value:

1. **OS keyring** (recommended — nothing is written to a config file in clear text)
2. **Environment variable** (`TRANSKRIBUS_USER` + `TRANSKRIBUS_PASSWORD`, or `TRANSKRIBUS_SESSION_ID`)

Either a user name and password (the server logs in and manages the session) or
a session id you already hold. A session id takes precedence when both are
available; it expires, so a user name and password is the better choice for a
long-running setup — and is what lets the server re-authenticate after a 401.

The keyring is never required: if it is unavailable — a headless Linux box with
no Secret Service, an unsupported platform, an install with `--omit=optional` —
or if it does not answer within 5 seconds, the server falls back to the
environment.

### Store the credentials in the OS keyring

Three entries under one service name, `transkribus-mcp` by default:
`user`, `password` and `session-id` (store only what you use).

> [!IMPORTANT]
> The commands below read the value from an interactive prompt rather than
> taking it as an argument, so it never lands in your shell history, in a
> command line, or in the launch environment of another process. Avoid pasting a
> password directly onto the command line.

#### macOS

Omitting the value after `-w` makes `security` prompt for it:

```bash
security add-generic-password -s "transkribus-mcp" -a "user" -w
security add-generic-password -s "transkribus-mcp" -a "password" -w
```

> [!NOTE]
> A login-keychain item belongs to the program that created it. The first time
> the server reads an item created by `security`, macOS shows a "…wants to use
> your confidential information stored in transkribus-mcp" dialog — choose
> **Always Allow** and it will not ask again. Until that is granted the read
> cannot complete: the server waits 5 seconds, then falls back to the
> environment variables, so a server started where nobody can answer the dialog
> behaves as if the keyring were empty rather than hanging.
>
> To avoid the dialog entirely, write the entry from the same Node.js runtime
> that will read it. The value is piped in on standard input, so it appears
> neither in a command line nor in a process environment (`ps -E` shows those).
> The prompt below is plain POSIX, so it behaves the same in `zsh` and `bash`:
>
> ```bash
> npm install -g @lazyants/transkribus-mcp-server   # the keyring module ships with it
> cd "$(npm root -g)/@lazyants/transkribus-mcp-server"
> printf 'Transkribus password: ' >&2; stty -echo; IFS= read -r TK_SECRET; stty echo; printf '\n' >&2
> printf '%s' "$TK_SECRET" | node -e '
>   const { Entry } = require("@napi-rs/keyring");
>   let value = "";
>   process.stdin.setEncoding("utf8");
>   process.stdin.on("data", (chunk) => { value += chunk; });
>   process.stdin.on("end", () => {
>     new Entry("transkribus-mcp", "password").setPassword(value);
>     console.log("stored");
>   });
> '
> unset TK_SECRET
> ```
>
> Repeat with `"user"` in place of `"password"`. A different Node.js
> installation later (a `nvm` switch, say) is a different program to the
> keychain, so the dialog can appear once more for it.

#### Windows (PowerShell)

`cmdkey` can only take the value as a command-line argument, which exposes it in
the process list. Read it from a hidden prompt instead and write it straight into
Windows Credential Manager via `CredWrite`. The credential's target name is
`<account>.<service>` — `user.transkribus-mcp` and `password.transkribus-mcp`
for the default service — which is exactly what the server reads back:

```powershell
Add-Type -Namespace TranskribusKeyring -Name Native -MemberDefinition @'
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public struct CREDENTIAL {
    public uint Flags;
    public uint Type;
    [MarshalAs(UnmanagedType.LPWStr)] public string TargetName;
    [MarshalAs(UnmanagedType.LPWStr)] public string Comment;
    public System.Runtime.InteropServices.ComTypes.FILETIME LastWritten;
    public uint CredentialBlobSize;
    public IntPtr CredentialBlob;
    public uint Persist;
    public uint AttributeCount;
    public IntPtr Attributes;
    [MarshalAs(UnmanagedType.LPWStr)] public string TargetAlias;
    [MarshalAs(UnmanagedType.LPWStr)] public string UserName;
}
[DllImport("advapi32.dll", CharSet = CharSet.Unicode, SetLastError = true)]
public static extern bool CredWriteW(ref CREDENTIAL credential, uint flags);
'@

function Set-TranskribusCredential {
    param([Parameter(Mandatory)][string]$Account, [Parameter(Mandatory)][string]$Prompt)
    $secure = Read-Host -AsSecureString $Prompt
    $blob = [Runtime.InteropServices.Marshal]::SecureStringToCoTaskMemUnicode($secure)
    try {
        $cred = New-Object TranskribusKeyring.Native+CREDENTIAL
        $cred.Type = 1                                  # CRED_TYPE_GENERIC
        $cred.Persist = 2                               # CRED_PERSIST_LOCAL_MACHINE
        $cred.TargetName = "$Account.transkribus-mcp"   # "<account>.<service>"
        $cred.UserName = $Account
        $cred.CredentialBlob = $blob
        $cred.CredentialBlobSize = $secure.Length * 2   # UTF-16 bytes, no terminator
        if (-not [TranskribusKeyring.Native]::CredWriteW([ref]$cred, 0)) {
            throw "CredWrite failed (Win32 error $([Runtime.InteropServices.Marshal]::GetLastWin32Error()))"
        }
        Write-Host "Stored '$Account' in Windows Credential Manager."
    } finally {
        [Runtime.InteropServices.Marshal]::ZeroFreeCoTaskMemUnicode($blob)
        $secure.Dispose()
        Remove-Variable secure, blob
    }
}

Set-TranskribusCredential -Account 'user' -Prompt 'Transkribus user (e-mail)'
Set-TranskribusCredential -Account 'password' -Prompt 'Transkribus password'
```

> Using a custom `TRANSKRIBUS_KEYRING_SERVICE` (e.g. `acme`)? Set `TargetName` to
> `user.acme` / `password.acme` to match — the server looks each value up under
> `<account>.<service>`.

#### Linux

```bash
secret-tool store --label="Transkribus user" service transkribus-mcp username user
secret-tool store --label="Transkribus password" service transkribus-mcp username password
# (each prompts for the value)
```

Once stored, MCP config files need no credentials at all.

### Use environment variables instead

```bash
export TRANSKRIBUS_USER=your-email@example.com
export TRANSKRIBUS_PASSWORD=your-password
```

Or, with a session you already hold:

```bash
export TRANSKRIBUS_SESSION_ID=your-session-id
```

### Environment variables

| Variable | Default | Description |
| --- | --- | --- |
| `TRANSKRIBUS_USER` | — | Account e-mail; used when the keyring has no `user` entry for the configured service |
| `TRANSKRIBUS_PASSWORD` | — | Account password; used when the keyring has no `password` entry |
| `TRANSKRIBUS_SESSION_ID` | — | An existing session id; used when the keyring has no `session-id` entry |
| `TRANSKRIBUS_KEYRING_SERVICE` | `transkribus-mcp` | Keyring service name. Override to connect to several Transkribus accounts at once — run one server instance per account, each with its own service name |

### Processing API credentials

The `transkribus_processing_*` tools talk to a different service with a different
auth scheme, but they need **no extra configuration**: the same
`TRANSKRIBUS_USER` + `TRANSKRIBUS_PASSWORD` are exchanged for an OIDC bearer token
(READCOOP SSO password grant, client `processing-api-client`) and refreshed
automatically. `TRANSKRIBUS_SESSION_ID` does not apply to them.

Two optional overrides:

```bash
export TRANSKRIBUS_ACCESS_TOKEN=your-bearer-token       # skip the token exchange entirely
export TRANSKRIBUS_PROCESSING_CLIENT_ID=custom-client   # non-default OIDC client
```

### Optional Processing v2 beta

Set `TRANSKRIBUS_PROCESSING_BACKEND=v2` in the MCP server's environment before
starting it. The default is `v1`; invalid values fail configuration. v2 uses
the documented staging host `https://api-staging.transkribus.org/v2`, with the
same OIDC credentials and PAGE/ALTO XML operations as v1. This selection affects
the Processing tools in both the full server and `transkribus-mcp-processing`.

| Backend | Job identifiers | Terminal statuses | Result retention | Tools |
|---|---|---|---|---|
| `v1` (default) | Positive integers, including numeric strings | `FINISHED`, `FAILED` | Two days | Submit, status, PAGE XML, ALTO XML |
| `v2` (beta, staging) | Positive integers, numeric strings, UUIDs | `FINISHED`, `FAILED`, `CANCELLED` | 24 hours after completion | The same four tools, plus longpoll and