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sceptre

MCP server

sceptre can run as a Model Context Protocol (MCP) stdio server, exposing OCR to any MCP-capable agent as a tool call instead of a subprocess invocation.

Running the server

Section titled “Running the server”
Terminal window
sceptre mcp --lang english

Requires the CLI built with the mcp feature (see Installation). sceptre mcp accepts the same shared overrides as the other subcommands — --lang, --threads, --backend, --accelerator, --text-threshold, --link-threshold, --canvas-size — used to build the Reader the server holds for the lifetime of the process. Configure the languages you need up front; there is no per-call language override.

The server communicates over stdio, so an agent host spawns it as a subprocess and talks JSON-RPC over its stdin/stdout. It is designed for a local, trusted client — the tool reads whatever path the client sends with the server process’s own filesystem privileges.

The readtext tool

Section titled “The readtext tool”
Parameter Type Description
image_path string (required) Filesystem path to the image to run OCR over.
detail boolean (optional, default true) When false, the response contains only recognized text (no box or confidence).

With detail: true (or omitted), the tool returns the full OcrResult as structured JSON — an array of lines, each with quad, text, and confidence. With detail: false, it returns { "lines": ["...", "..."] } — just the recognized text, for callers that only want the words.

On an OCR failure, the tool returns an MCP tool error containing OCR failed: <message> rather than throwing a protocol-level error.

Example invocation

Section titled “Example invocation”

An MCP client calling the tool sends parameters like:

{
  "name": "readtext",
  "arguments": {
    "image_path": "/data/receipts/receipt-001.png",
    "detail": true
  }
}

and receives a structured result equivalent to:

{
  "lines": [
    { "quad": { "points": [...] }, "text": "TOTAL", "confidence": 0.98 },
    { "quad": { "points": [...] }, "text": "$42.10", "confidence": 0.95 }
  ]
}