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prawo-pl-mcp

One MCP server for Polish legal data.

Ten independent connectors - case law, legislation, the company register, tax rulings, public procurement, data-protection decisions, plus EU extras - behind four tools. Each connector stays a separate package with its own repository; this server spawns them on demand and translates between their conventions.

"Prawo" is Polish for "law"; the name follows yargi-mcp's move of naming a country server in its own language.

Why an aggregator

The connectors cover Polish legal data well, but as separate MCP servers, one per database - ten installs and ten config entries before the first question. yargi-mcp showed the fix for Turkish law: 16 institutions, one server. prawo-pl-mcp does the same for Poland:

  • Four tools instead of 42. pl_list_sources, pl_search, pl_get_document, pl_call - fewer tool schemas means less context spent before the LLM starts working.

  • One convention. The connectors grew organically: dateFrom here, date_from there, pages counted from 0 or from 1 depending on the repo. Here page is always 1-based and dates are always date_from/date_to (YYYY-MM-DD); the translation happens inside. One name per concept applies to the aggregator's own tools too: page is the page parameter of both pl_search and pl_get_document (page_number still works as a deprecated alias), and pl_call takes arguments or its alias args.

  • Native names on the table. Every catalog entry carries native_params - the native parameter name each unified one maps to for that source, so article_number (eu-compliance) is visible without spawning the connector or reading an upstream error. pl_call checks the names it was given against the connector's own schema and says which one it meant.

  • Nothing preinstalled. Connectors run as subprocesses via npx -y / uvx, downloaded on the first call to a given source and kept alive afterwards. A source that cannot start reports a readable error while the rest keep working.

  • Paginated documents. Full judgment and act texts are chunked at ~5000 characters per page (yargi-mcp's pattern), so a 200-page ruling does not flood the context window. Sources that paginate server-side (isap) get the page forwarded natively and are reported as pagination: "native" - the aggregator does not re-cut an already-cut page and does not invent a total_pages it cannot know.

Related MCP server: mcp-nsa

Coverage

Source id

What

Institution / database

Connector

Runtime

saos

Case law: common courts, Supreme Court, Constitutional Tribunal + citator

SAOS

mcp-saos

npx

nsa

Case law: administrative courts (NSA + 16 WSA)

CBOSA

mcp-nsa

npx

isap

Legislation: Dziennik Ustaw + Monitor Polski, 96k+ acts

Sejm ELI API

mcp-isap

npx

krs

Company register: extracts, history, board composition

KRS API (Ministry of Justice)

mcp-krs

npx

eureka

Tax rulings: 550k+ individual interpretations

EUREKA (Ministry of Finance)

mcp-eureka

npx

kio

Public procurement: National Appeal Chamber rulings

orzeczenia.uzp.gov.pl

kio-orzeczenia-mcp

uvx

uodo

GDPR enforcement: Polish DPA decisions, fines, stats

orzeczenia.uodo.gov.pl

uodo-orzeczenia-mcp

uvx

eu-sparql

EU law: EUR-Lex by CELEX, CJEU by ECLI, GDPRhub

Cellar SPARQL

mcp-eu-sparql

npx

eu-compliance

14 EU regulations offline (GDPR, AI Act, DORA, NIS2...)

Local SQLite corpus

mcp-eu-compliance

npx

legalize

Law-as-git: 32 jurisdictions, versioned by commit

legalize-dev

legalize-mcp

uvx

Polish sources are tagged group: pl, EU extras group: eu - filter with pl_list_sources(group="pl").

Tools

Tool

What it does

pl_list_sources

Catalog of sources (no subprocess spawned). With source_id: live tool schemas of one connector.

pl_search

Search any source with normalized parameters; source-specific filters via extra.

pl_get_document

Full document by identifier (judgment id, ELI, KRS number, signature...), paginated.

pl_call

Any native tool of any connector: citator, DPA statistics, board composition, regulation comparison...

pl_coverage

Declare what this connector covers, when each family was captured, and - explicitly - what it does NOT cover. Every gap carries a fallback.

The typical flow an LLM follows (spelled out in the server's instructions): pl_list_sourcespl_searchpl_get_document, with pl_call for the specialized tools each connector brings.

Install

Requires Python ≥ 3.11 plus the runtimes of the sources you use: Node.js ≥ 18 for npx sources, uv for uvx sources. If a runtime is missing, its sources report source_unavailable and the rest work.

Claude Code

claude mcp add pl-legal -- uvx prawo-pl-mcp

Claude Desktop / any MCP client (stdio)

{
  "mcpServers": {
    "pl-legal": {
      "command": "uvx",
      "args": ["prawo-pl-mcp"]
    }
  }
}

Remote (Streamable HTTP)

uvicorn prawo_pl_mcp.asgi:app --host 0.0.0.0 --port 8000

Open by default (public, read-only data). Set PRAWO_PL_MCP_API_KEY to require X-API-Key: <key> or Authorization: Bearer <key> on every request.

Configuration

Env

Default

Meaning

PRAWO_PL_MCP_CMD_<ID>

-

Override the spawn command for a source, e.g. PRAWO_PL_MCP_CMD_SAOS="node C:/dev/mcp-saos/dist/index.js" for a local checkout. <ID> = source id, uppercase, -_.

PRAWO_PL_MCP_INIT_TIMEOUT

180

Seconds allowed for a connector's first start (includes package download).

PRAWO_PL_MCP_TIMEOUT

90

Seconds per tool call after startup.

PRAWO_PL_MCP_AUDIT_DIR

~/.matematic/audit

Where the JSONL audit log goes.

PRAWO_PL_MCP_API_KEY

-

ASGI mode only: require this API key (dual-channel).

Architecture

The aggregator is a thin proxy (ADR 0001). Connectors are not imported, vendored or forked; the aggregator speaks MCP to them over stdio the same way any client would. The whole layer is a source registry (one dataclass entry per connector), a lazy subprocess pool, a parameter translator and a paginator. Adding a source means adding a registry entry.

LLM client ──MCP──▶ prawo-pl-mcp ──MCP/stdio──▶ npx @matematicsolutions/mcp-saos
                        │         ──MCP/stdio──▶ uvx kio-orzeczenia-mcp
                        │         ──MCP/stdio──▶ ... (spawned on first use)
                        └─ registry + param mapping + 5000-char pagination

Every call lands in a JSONL audit log (timestamp, tool, source, parameter hash, latency - never document content).

Development

git clone https://github.com/matematicsolutions/prawo-pl-mcp && cd prawo-pl-mcp
uv sync --extra dev
uv run pytest          # offline tests: registry, dispatch mapping, pagination, drift
uv run prawo-pl-mcp    # stdio server

License

Apache-2.0. Individual connectors carry their own licenses (MIT or Apache-2.0), their own rate limits and their own terms toward upstream databases - the aggregator adds no caching and no transformation beyond pagination, so each connector's constraints apply unchanged.

Available Tools

4 tools
pl_callA
Read-onlyIdempotent

Escape hatch: call any native tool of any registered source.

For operations the unified tools do not cover: citator (saos_cite_check), DPA statistics (uodo_stats), procurement-article search (kio_by_pzp_article), board composition (get_board), regulation comparison (eu_compare), tax category dictionary (list_categories)... arguments (alias: args - both accepted, pass only one) is an object keyed by the NATIVE parameter names of that tool, passed verbatim. The native names of the common ones are in native_params from pl_list_sources; for everything else read the live schema via pl_list_sources(source_id=...). Wrong parameter names are caught here against the connector's schema, before the call leaves the aggregator.

Errors: unknown_source, unknown_tool (not exposed by that source), invalid_arg (missing required or misspelled parameter name), source_unavailable, upstream_error (connector's own error code in message).

ParametersJSON Schema
NameRequiredDescriptionDefault
argsNo
toolYes
sourceYes
argumentsNo

Output Schema

ParametersJSON Schema
NameRequiredDescription
resultYes

TDQS

A4.6/5.0
Behavior4/5

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

Annotations already include readOnlyHint, idempotentHint, and destructiveHint=false. The description adds meaningful context: parameters are passed verbatim, validation happens at the aggregator before forwarding, and specific error codes are enumerated. This enriches the behavioral model without contradicting annotations.

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

Conciseness4/5

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

The description is well-structured: a concise opening, practical examples, parameter details, and a list of errors. Slightly long for an escape hatch but every sentence contributes necessary information.

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

Completeness5/5

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

For a generic escape-hatch tool, the description is highly complete. It covers use cases, parameter semantics, how to discover native names, validation behavior, and error handling. The output schema is present, so return-value details are not needed.

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

Parameters4/5

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

Schema description coverage is 0%, so the description compensates well. It explains the 'arguments'/'args' alias and clarifies that either can be used (not both), and that keys must be native parameter names, directing to pl_list_sources for discovering them. Source and tool are self-explanatory given the context.

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 function: 'call any native tool of any registered source.' It distinguishes itself from sibling unified tools by positioning as an 'escape hatch' for operations not covered, with concrete examples (citator, DPA statistics, etc.).

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?

Explicitly tells when to use the tool: 'For operations the unified tools do not cover.' It also provides alternatives for finding native parameter names (pl_list_sources) and lists possible error cases, fully guiding the agent.

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

pl_get_documentA
Read-onlyIdempotent

Fetch the full document (judgment, act text, register extract...) from a source.

document_id format depends on the source - numeric id (saos), hex doc_id (nsa), ELI (isap), KRS number (krs), signature (kio, uodo)... - see the document_id field in pl_list_sources. Long documents are paginated at ~5000 characters per page: response is JSON with content, page, total_pages, has_more - iterate page while has_more (page is 1-based, exactly as in pl_search; page_number is a deprecated alias kept for backward compatibility, and is echoed in the response for the same reason). Sources that paginate the document themselves (isap) report pagination: "native" and carry their own page footer inside content. Some sources need extra (e.g. eu-compliance: {"regulation": "GDPR"}).

Errors: unknown_source, invalid_arg (missing required extra, page < 1, conflicting page/page_number), source_unavailable, upstream_error (e.g. connector's not_found - check the identifier or search first).

ParametersJSON Schema
NameRequiredDescriptionDefault
pageNo
extraNo
sourceYes
document_idYes
page_numberNo

Output Schema

ParametersJSON Schema
NameRequiredDescription
resultYes

TDQS

A4.7/5.0
Behavior5/5

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

Annotations already mark the tool as read-only, idempotent, and non-destructive. The description adds substantial behavioral detail: pagination at ~5000 characters, the exact response fields (content, page, total_pages, has_more), the deprecated page_number alias, native pagination for isap, and a concrete extra example for eu-compliance. It also enumerates error types, enriching the transparency beyond the annotation baseline. No contradiction with annotations exists.

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

Conciseness4/5

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

The description is a single dense paragraph, but every sentence conveys necessary information: pagination, native pagination, extra per source, and error codes. No filler or redundancy. While not broken into bullet points, its length is justified by the tool's complexity. It is front-loaded with the main purpose.

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

Completeness5/5

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

Given the tool's high complexity (source-specific IDs, optional extra, pagination modes, error taxonomy), the description covers all functional aspects necessary for correct invocation. It includes edge cases like page_number conflicts, missing required extra, and upstream_error with guidance to search first. An output schema exists, so return-value details are not needed, and the description's pagination overview complements it.

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

Parameters5/5

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

Schema description coverage is 0%, so the description bears full responsibility for parameter meaning. It does this thoroughly: document_id is explained with source-specific formats, page is clarified as 1-based, extra is given a concrete example, and page_number is identified as a deprecated alias. Source is implicitly understood from pl_list_sources. This fully compensates for the empty 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 opening phrase 'Fetch the full document' uses a specific verb and resource, clearly distinguishing it from sibling tools like pl_search (search) and pl_list_sources (list sources). It also delineates scope by enumerating document types and referencing per-source ID 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?

Usage context is clear: it explains how to fetch documents and how pagination works, and it references pl_list_sources for document_id format and pl_search for pagination comparability. However, it does not explicitly state when to use this tool versus alternatives or provide 'when not to use' exclusions, though it hints at searching first before fetching.

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

pl_list_sourcesA
Read-onlyIdempotent

List available Polish/EU legal data sources, or inspect one source's live tool schemas.

Without arguments: full catalog (id, coverage, capabilities, native tool names, and native_params - the NATIVE parameter name each unified parameter maps to, e.g. eu-compliance pl_get_document -> {"tool": "eu_article", "document_id": "article_number"}) - reads a local registry, spawns nothing. With source_id: connects to that connector (lazy spawn on first use) and returns its live tools/list with input schemas - needed for native tools that the unified tools do not cover. Optional group filter: 'pl' or 'eu'.

Errors: unknown_source (bad source_id), source_unavailable (connector could not start).

ParametersJSON Schema
NameRequiredDescriptionDefault
groupNo
source_idNo

Output Schema

ParametersJSON Schema
NameRequiredDescription
resultYes

TDQS

A4.7/5.0
Behavior5/5

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

Annotations declare readOnly, idempotent, and non-destructive hints, and the description adds valuable context: it explicitly states that the no-arg mode 'reads a local registry, spawns nothing' and that the source_id mode 'connects to that connector (lazy spawn on first use)'. It also discloses possible errors, adding transparency beyond the annotations.

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

Conciseness4/5

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

The description is dense and well-structured, using a first-sentence summary followed by mode-specific details and error notes. It is longer than necessary but every sentence provides useful information, making it efficient rather than verbose.

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

Completeness5/5

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

The description covers both execution modes, optional filters, return values (catalog fields, live schemas), side effects (lazy spawn), and error cases. Given the tool's two-mode complexity and the presence of an output schema, this is a complete and self-sufficient description.

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

Parameters5/5

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

Despite 0% schema description coverage, the description thoroughly explains both parameters: source_id triggers connector inspection, group filters by 'pl' or 'eu', and no arguments yields the full catalog. It even illustrates the native_params mapping with an example, fully compensating for the schema's lack of descriptions.

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 function: 'List available Polish/EU legal data sources, or inspect one source's live tool schemas.' It specifies both a verb and resource, and distinguishes it from sibling tools like pl_search and pl_get_document by focusing on discovery and schema inspection.

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 explains when to use each mode: 'Without arguments' for the full catalog, 'With source_id' for live schemas, and 'Optional group filter' for narrowing by 'pl' or 'eu'. It also notes the use case for native tools not covered by unified tools, but does not explicitly name alternative tools or when-not-to-use scenarios.

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. 4 tool updatesv0.1.3
    • First observedpl_call
    • First observedpl_get_document
    • First observedpl_list_sources
    • First observedpl_search

TDQS

A4.8/5.0

Scored across 4 tools

Disambiguation5/5

Each tool occupies a distinct layer: discovery (pl_list_sources), search (pl_search), retrieval (pl_get_document), and native access (pl_call). No overlap; pl_call is explicitly for operations not covered by the unified tools.

Naming Consistency5/5

All tools share a consistent 'pl_' prefix with clear verb-based names (list_sources, search, get_document, call). The pattern is uniform and predictable, with no mixing of conventions.

Tool Count5/5

Four tools is well-scoped for an aggregator server: it provides the essential operations plus an escape hatch for source-specific features, without bloat.

Completeness5/5

The tool set covers the full lifecycle of legal data access: discover sources, search, fetch documents, and call any native tool for specialized operations. The escape hatch ensures no dead ends.

Maintenance

ActivityMaintained
ResponsivenessNo issues

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