transkribus-mcp-server

MCP server for the Transkribus REST API. Manage collections, documents, HTR/OCR recognition, models, and more through the Model Context Protocol.

304 tools 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 Metagrapho Processing API (https://transkribus.eu/processing/v1), OIDC bearer auth via account.readcoop.eu — the 4 transkribus_processing_* tools.

Mind the version. Some Transkribus material still shows /processing/v2 and a config.modelId field. That path returns 404; the live service is /processing/v1 and takes config.textRecognition.htrId.

Installation

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

Or run directly:

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:

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:

Terminal

Copy

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:

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

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

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

Or, with a session you already hold:

export TRANSKRIBUS_SESSION_ID=your-session-id

Environment variables

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:

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

Entry Points

Use split servers to reduce context size — pick only the splits you need.

Uploading a document

To ingest a document, use this three-step flow: