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MCP Saos

Searches Polish court judgments through SAOS and provides judgment retrieval, case-number lookup, and citation-status checks.

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Install MCP Saos

Pick your client, then add it in one click or paste the config.

STDIONode.js
~/Library/Application Support/Claude/claude_desktop_config.json
claude_desktop_config.json
{
  "mcpServers": {
    "mcp-saos": {
      "command": "npx",
      "args": [
        "-y",
        "@matematicsolutions/mcp-saos"
      ]
    }
  }
}

Settings → Developer → Edit Config, merge this into mcpServers, then fully quit and reopen Claude Desktop.

Install not yet sandbox-tested— we haven't run this command through our automated sandbox yet. Not a red flag; we're working through the catalog.

Overview

The mcp-saos MCP server connects AI agents to SAOS, Poland’s public court-judgment database, through a stdio MCP process. It supports full-text and filtered searches, judgment retrieval by ID, case-number searches, and a heuristic citator for later treatment. Reach for it when working with Polish case law and needing source-linked results, while verifying important conclusions against official court sources.

Use cases

  • Search Polish judgments by legal issue or court
  • Retrieve a complete judgment for review
  • Find judgments using a case number
  • Check later citations for possible departures
  • Render structured judgment citations in a legal agent

Key features

  • Full-text and filtered SAOS search
  • Judgment retrieval by ID
  • Case-number lookup
  • Heuristic citation-status checks
  • Structured citation metadata
  • Live public API access without an API key

Tools4

What MCP Saos lets your agent do. Expand a tool for its parameters.

Self-reported~80 tokens of context

Security & health

What it can reach and how reliably it runs — from our own checks, not the maintainer’s claims.

ActiveLast checked 3d ago

Recent health check succeeded.

8/8 checks healthy over the last 51d

Supply-chain signal

No high-severity advisories surfaced by our automated scan.

Critical 0High 0Medium 0Low 0

Scanned 16h ago via OSV.dev · @matematicsolutions/mcp-saos (npm)

Adoption & maintenance

Factual signals from GitHub, npm, and our automated checks — not a rating.

GitHub stars2Stargazers on the source repository.
npm downloads332Package downloads in the last 30 days.
Last commit14d agoMost recent push to the default branch.
Tools exposed4Callable tools this server registers over MCP.

How MCP Saos works

What mcp-saos does

The mcp-saos MCP server exposes the SAOS public REST API to MCP-compatible AI clients. SAOS contains Polish judgments from common courts, the Supreme Court, the Constitutional Tribunal, and the National Appeal Chamber. It does not provide indexed data from administrative courts such as WSA or NSA.

The server is intended for research workflows involving Polish case law. Responses include caveats about database coverage, and the project’s citation contract can provide structured citation records containing a title, URL, snippet, and related metadata.

How it works

The process communicates with an MCP client over standard input and output using JSON-RPC. It sends requests to SAOS at https://www.saos.org.pl/api, including the judgment search and individual judgment endpoints. HTTP and JSON handling use Node’s built-in HTTPS support; the production MCP dependency is the official SDK.

The saos_cite_check tool searches for later judgments that cite a supplied case signature. It examines text near the cited signature for phrases that may indicate a departure from, or loss of authority of, the earlier judgment. Results use verdicts such as przelamanie_wykryte, uchwala_skladu_powiekszonego, nadal_cytowany, and brak_cytowan_w_saos, with text fragments for human review.

Setup and configuration

The mcp-saos MCP server requires Node.js 18 or newer, npm 9 or newer, and internet access to the live SAOS API. The published package can be started without cloning the repository:

Terminal
npx -y @matematicsolutions/mcp-saos

For a source build, clone the repository, run npm install, then run npm run build. The generated entry point is dist/index.js. A stdio client configuration uses npx with the package name, or invokes that built JavaScript file with Node. Diagnostic output goes to stderr, leaving stdin and stdout available for MCP traffic.

Tools and capabilities

  • search performs full-text searches and supports filters for court, judge, legal basis, and dates.
  • get_judgment retrieves a complete SAOS judgment by its identifier.
  • search_by_case searches using a case number such as I ACa 772/13.
  • saos_cite_check looks for later citing judgments and possible overruling language.

Limitations and notes

The citator is heuristic rather than a definitive statement of whether a judgment remains good law. It checks the top citing results and a defined phrase set, so an absence of matches does not establish that a judgment is still current. Each result should be reviewed by a legal professional and checked against primary sources where the issue matters.

SAOS coverage varies by court and period. Current judgments are well represented in some areas, but certain Supreme Court resolutions may appear only as citations. Administrative-court searches return no indexed results. The database can also contain OCR-related date errors, making the case number more dependable than judgmentDate in affected records.

The server enforces a minimum pageSize of 10 because smaller values cause an SAOS error. The mcp-saos MCP server does not require an API key, but it does require network access. The software is MIT-licensed; judgment data is provided through Fundacja ePanstwo’s public API under its stated open-use terms.

Read the full README View source on GitHub

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Frequently Asked Questions about MCP Saos

mcp-saos is an MCP server that connects AI agents to SAOS, Poland’s public court judgment database. It provides search for full-text and filtered results, retrieval by judgment ID, case-number lookup, and a citator that finds later citing judgments and flags possible overruling language.

Run `npx -y @matematicsolutions/mcp-saos` in an MCP client configured for stdio. Alternatively, clone the repository, install dependencies with npm, run `npm run build`, and invoke `dist/index.js` with Node.

No, mcp-saos uses SAOS’s public REST API without an API key. It does require Node.js 18 or newer, npm 9 or newer for the package workflow, and internet access to reach the live service.

No, SAOS does not index WSA or NSA administrative-court data. Searches for `courtType=ADMINISTRATIVE` return empty results; the available coverage includes common courts, the Supreme Court, the Constitutional Tribunal, and the National Appeal Chamber.

No, `saos_cite_check` is a heuristic. It scans selected later citing judgments for a defined set of departure phrases near the cited signature, so no detected matches do not prove that a judgment remains current.

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