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Yandex Vision OCR MCP

npm version npm downloads License: MIT Node Tests

A Model Context Protocol (MCP) server that exposes Yandex Vision OCR as tools, so any MCP-compatible client — opencode, Claude Desktop, Cursor, Cline — can extract text from images and PDFs.

Features

  • recognize_text — synchronous OCR for images (JPEG/PNG/WEBP/HEIC/HEIF) and single-page PDFs.

  • recognize_pdf — asynchronous OCR for PDFs (single- or multi-page) and large files, via recognizeTextAsync + getRecognition polling.

  • Recognition models — printed text, multi-column, handwritten, tables, Markdown, and math formulas (LaTeX), selectable per call.

  • Accepts a local file path or raw base64 content.

  • Recognition languages selectable between ru and en (default ru; combine as ["ru","en"] for mixed text). Auto-detect is not supported by this endpoint.

  • Three output formats: text (default), markdown, or full json (the raw textAnnotation with blocks/lines/words/tables/entities).

  • Zero-touch error handling — API failures are returned as isError tool results, never crashes.

  • Lazy credentials — the server boots and lists tools even before YANDEX_* env vars are set, surfacing a clear error only on the first call.

Related MCP server: yandex-searchapi-mcp

Prerequisites

  1. Node.js ≥ 20.

  2. A Yandex Cloud account with the Vision/OCR API enabled.

  3. A folder ID + either an API key (recommended) or an IAM token. See the authentication docs.

Quick start

# Run directly with npx (no install needed)
npx -y yandex-vision-ocr-mcp

Then wire it into your MCP client (see Configuration).

Configuration

The server reads credentials from environment variables:

Variable

Required

Description

YANDEX_FOLDER_ID

optional

Yandex Cloud folder ID. Only sent as x-folder-id when set — the API key already scopes requests, so you can usually leave this unset. If set, it must match the key's folder.

YANDEX_API_KEY

one of

API key (recommended for long-lived usage).

YANDEX_IAM_TOKEN

one of

Short-lived IAM token (~12h). Use instead of an API key.

See .env.example for a template.

Models

Pass model to any tool to pick the recognition behaviour:

Model

Best for

page (default)

Single-column printed text.

page-column-sort

Multi-column printed text.

handwritten

Mixed handwritten + printed text (Russian, English).

table

Tables (Russian, English).

markdown

Printed text, also returned as Markdown.

math-markdown

Math formulas, returned as Markdown with LaTeX (e.g. $a^2 + b^2$).

Tip: use format: "markdown" together with the markdown / math-markdown models to receive the model's Markdown output directly.

Tools

Both tools accept the same input shape:

Argument

Type

Default

Description

path

string

Local file to OCR. Provide this or base64.

base64

string

Base64 content (data: URIs accepted). Provide this or path.

mimeType

string

inferred

Explicit MIME type override.

languages

string[]

["ru"]

Recognition languages, selectable: ru, en (e.g. ["ru","en"] for mixed).

model

string

page

Recognition model — see Models.

format

text | markdown | json

text

Output format.

Supported formats: JPEG, PNG, WEBP, HEIC, HEIF (images) and PDF. The mimeType sent to the API is derived automatically (you can pass a standard MIME type via mimeType if needed). BMP/TIFF are not supported by the service.

  • recognize_text — synchronous. Best for images and single-page PDFs.

  • recognize_pdf — asynchronous (submit + poll). Best for multi-page PDFs and large files. Requires the input to be a PDF.

Example result (text format)

Hello World
Yandex OCR

Connect to opencode

Add the server to your opencode.json under mcp:

{
  "mcp": {
    "yandex-vision-ocr": {
      "type": "local",
      "command": ["npx", "-y", "yandex-vision-ocr-mcp@latest"],
      "enabled": true,
      "environment": {
        "YANDEX_FOLDER_ID": "b1g...",
        "YANDEX_API_KEY": "your-api-key"
      }
    }
  }
}

If you cloned the repo instead, replace the command with ["node", "/absolute/path/to/yandex-vision-ocr-mcp/build/index.js"].

Connect to Claude Desktop / Cursor / Cline

{
  "mcpServers": {
    "yandex-vision-ocr": {
      "command": "npx",
      "args": ["-y", "yandex-vision-ocr-mcp@latest"],
      "env": {
        "YANDEX_FOLDER_ID": "b1g...",
        "YANDEX_API_KEY": "your-api-key"
      }
    }
  }
}
{
  "mcpServers": {
    "yandex-vision-ocr": {
      "command": "npx",
      "args": ["-y", "yandex-vision-ocr-mcp@latest"],
      "env": {
        "YANDEX_FOLDER_ID": "b1g...",
        "YANDEX_API_KEY": "your-api-key"
      }
    }
  }
}

Local development

git clone https://github.com/chupre/yandex-vision-ocr-mcp.git
cd yandex-vision-ocr-mcp
npm install
npm run build      # type-check + compile to build/
npm test           # run the vitest suite
npm run dev        # run the server from source via tsx
npm run inspector  # open the MCP Inspector UI against the build

Useful scripts:

Script

Description

npm run build

Compile TypeScript to build/.

npm run typecheck

Type-check without emitting.

npm test

Run the offline test suite.

npm run dev

Run the server from source (tsx).

npm run inspector

Launch the MCP Inspector for manual testing.

Testing

The offline suite covers input handling, MIME inference, response formatting, the HTTP client (via a fake transport, no network), tool wiring, and a full MCP round-trip over an in-memory transport.

Live integration tests hit the real Yandex OCR API and are skipped unless credentials and sample files are provided:

YANDEX_FOLDER_ID=... YANDEX_API_KEY=... \
YOCR_LIVE_IMAGE=./sample.png \
YOCR_LIVE_PDF=./sample.pdf \
npx vitest run tests/live.test.ts

Docker

docker build -t yandex-vision-ocr-mcp .
docker run --rm -i \
  -e YANDEX_FOLDER_ID=b1g... \
  -e YANDEX_API_KEY=... \
  yandex-vision-ocr-mcp

API coverage

This server targets the Yandex Cloud Vision OCR REST API (ocr.api.cloud.yandex.net/ocr/v1):

Route

Method

Used for

/recognizeText

POST

Synchronous recognition (recognize_text).

/recognizeTextAsync

POST

Start async recognition (recognize_pdf).

/getRecognition

GET

Poll for the async result.

Concepts: OCR overview · image · PDF · handwritten.

License

MIT

Available Tools

2 tools
recognize_pdfA

Recognize text in a PDF document (single or multi-page) using Yandex Vision OCR via asynchronous recognition (recognizeTextAsync + getRecognition polling). Use this for PDFs and large files. Provide a local file 'path' or 'base64' content, and pick a 'model' (default 'page').

ParametersJSON Schema
NameRequiredDescriptionDefault
pathNoAbsolute or relative path to a local file to read and OCR. Provide this OR 'base64'.
base64NoBase64-encoded file content. May be a data URI ('data:<mime>;base64,...'). Provide this OR 'path'.
mimeTypeNoExplicit MIME type override (e.g. 'image/jpeg'). Inferred from the file when omitted.
languagesNoRecognition languages (selectable). Use ['ru'], ['en'], or ['ru','en'] for mixed text. Defaults to ['ru']. This Yandex OCR endpoint does not support auto-detect.
modelNoRecognition model. 'page' (default): single-column printed text. 'page-column-sort': multi-column text. 'handwritten': mixed handwritten + printed (ru/en). 'table': tables (ru/en). 'markdown': printed text with Markdown output. 'math-markdown': math formulas (LaTeX in Markdown).page
formatNoOutput format. 'text' (default) returns recognized plain text. 'markdown' returns the model's Markdown output when available (markdown/math-markdown models), otherwise plain text. 'json' returns the full textAnnotation (blocks/lines/words/tables/markdown).text

TDQS

A4.2/5.0
Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description transparently discloses the asynchronous recognition process (recognizeTextAsync + getRecognition polling) and language limitations (no auto-detect). This is adequate disclosure for a non-destructive read operation, though rate limits or size constraints are not mentioned.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is two sentences, front-loading the core purpose and immediately following with usage guidance. Every sentence contributes essential information without redundancy.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool's complexity (6 parameters, async polling, no output schema), the description covers the key behavioral aspects and parameter choices. It explains the async workflow and language limitations, but could have elaborated on the polling mechanism or return value format. Still, it is largely complete for an AI agent.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the baseline is 3. The description adds minor value by summarizing model purposes (e.g., 'page-column-sort' for multi-column text) and the choice between path and base64, but these details are already present in the schema. No significant new information is provided.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description explicitly states it recognizes text in a PDF document using Yandex Vision OCR, with details on async processing. This clearly distinguishes it from the sibling 'recognize_text' tool, which likely handles non-PDF formats.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description indicates use for PDFs and large files, providing context on when to apply it. While it doesn't explicitly list when not to use it or contrast with alternatives, the guidance is clear and sufficient for the intended use case.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

recognize_textA

Recognize text in an image (JPEG/PNG) or a single-page PDF using Yandex Vision OCR (synchronous). Picks the recognition model via 'model' (default 'page' for printed text; 'handwritten', 'table', 'markdown', etc.). Provide a local file 'path' or 'base64' content. For multi-page/large PDFs, use recognize_pdf instead.

ParametersJSON Schema
NameRequiredDescriptionDefault
pathNoAbsolute or relative path to a local file to read and OCR. Provide this OR 'base64'.
base64NoBase64-encoded file content. May be a data URI ('data:<mime>;base64,...'). Provide this OR 'path'.
mimeTypeNoExplicit MIME type override (e.g. 'image/jpeg'). Inferred from the file when omitted.
languagesNoRecognition languages (selectable). Use ['ru'], ['en'], or ['ru','en'] for mixed text. Defaults to ['ru']. This Yandex OCR endpoint does not support auto-detect.
modelNoRecognition model. 'page' (default): single-column printed text. 'page-column-sort': multi-column text. 'handwritten': mixed handwritten + printed (ru/en). 'table': tables (ru/en). 'markdown': printed text with Markdown output. 'math-markdown': math formulas (LaTeX in Markdown).page
formatNoOutput format. 'text' (default) returns recognized plain text. 'markdown' returns the model's Markdown output when available (markdown/math-markdown models), otherwise plain text. 'json' returns the full textAnnotation (blocks/lines/words/tables/markdown).text

TDQS

A4.4/5.0
Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description carries full burden. It discloses synchronous operation, supported MIME types, model behaviors, and language limitations (no auto-detect, only ru/en). It could mention error handling or response size, but overall transparency is good.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is a single efficient paragraph of 3-4 sentences, front-loaded with core purpose. Every sentence adds value: format support, model options, input alternatives, and sibling tool reference. No wasted words.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given 6 parameters, 100% schema coverage, and no output schema, the description covers input sources, model options, language limits, and sibling tool. It omits error handling and output format details (but format parameter covers that). Adequate for the tool's simplicity.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so baseline is 3. The description adds context about model use cases and mutual exclusivity of path/base64, but does not significantly deepen understanding beyond schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool's purpose: recognize text in images or single-page PDFs using Yandex Vision OCR (synchronous). It specifies supported formats and distinguishes from the sibling tool 'recognize_pdf' by noting multi-page PDFs should use that tool.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description provides explicit guidance on when to use this tool vs 'recognize_pdf' for multi-page/large PDFs. It also explains input options (path vs base64), model selection, and output formats, giving clear usage context.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

Tool Schema Changelog

Recent tool additions, removals, and schema changes observed during successful MCP inspections.

  1. 2 tool updatesv0.3.0
    • First observedrecognize_pdf
    • First observedrecognize_text

TDQS

A4.3/5.0

Scored across 2 tools

Disambiguation5/5

The two tools have clearly distinct purposes: one for images and single-page PDFs (synchronous), the other for multi-page/large PDFs (asynchronous). No overlap in functionality.

Naming Consistency4/5

Both tools follow the 'recognize_' prefix pattern with clear suffixes ('pdf' and 'text'), making them predictable and self-explanatory.

Tool Count4/5

Two tools is minimal but appropriate for a focused OCR server. It covers the core distinction between image/single-page and multi-page PDF processing without unnecessary complexity.

Completeness4/5

The tool surface covers the essential OCR use cases: image and PDF text recognition. The model parameter handles handwritten, table, and markdown, so no major gaps.

Maintenance

ActivityStale
ResponsivenessNo issues

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