ovf-data-mcp 0.1.1

Agent-friendly access to public Hungarian water-management datasets

ovf-data-mcp

Agent-friendly, read-only access to public Hungarian water-management data from the Országos Vízügyi Főigazgatóság (OVF).

[!WARNING] This repository is an experimental proof of concept, not a finished or supported production service. Interfaces and upstream integrations may change. See TODO.md for known limitations.

vizugy supports the investigation workflow agents actually need:

discover → resolve stations → inspect coverage → explain query → retrieve or aggregate → cite

The same application logic is exposed through a composable CLI and a local MCP server. The CLI is the primary interface; MCP tools are thin adapters over identical operations.

What it can do

• Discover and inspect public OVF ArcGIS datasets.
• Search surface-water stations by name, municipality, or watercourse.
• Find the nearest stations to WGS84 coordinates.
• List authoritative measurement codes, units, accepted ranges, and data types.
• Inspect temporal coverage before requesting observations.
• Retrieve compact, bounded operational or historical time series.
• Aggregate observations upstream by day, ten-day period, month, or year.
• Explain resolved identifiers and query semantics without fetching values.
• Return structured provenance and explicit upstream caveats.

It deliberately does not interpret hydrology, detect anomalies, expose arbitrary SQL, or provide unrestricted bulk access. The agent remains responsible for analysis.

Data sources

Source	Purpose	Status
VRAQuery OpenAPI	Stations, measurement catalogues, coverage, observations, aggregation	Officially documented
OVF ArcGIS REST	Spatial dataset discovery and layer metadata	Public; metadata quality varies
data.vizugy.hu	Official public-data frontend and anonymous access flow	Public frontend

Operational observations may be preliminary or unchecked. For official proceedings or guaranteed checked data, follow OVF's formal data-request process.

Installation

Run the MCP server directly from PyPI without cloning the repository:

uvx ovf-data-mcp

This command becomes available after the first PyPI release.

Add it to Claude Code for the current user:

claude mcp add --scope user ovf-data -- uvx ovf-data-mcp

For source development, use Python 3.11+ and uv:

git clone https://github.com/kalcifield/ovf-data-mcp.git
cd ovf-data-mcp
uv sync --extra test

Run commands from the checkout:

uv run vizugy --help
uv run ovf-data-mcp

After packaging or installation, use vizugy and ovf-data-mcp directly.

Quick investigation

1. Resolve a station

uv run vizugy stations search Budapest --watercourse Duna --limit 10

Results use stable namespaced IDs such as surface:1026.

Find stations by coordinates:

uv run vizugy stations nearest 47.4979 19.0402 --limit 5

2. Inspect available measurements and coverage

uv run vizugy catalog measurements

uv run vizugy observations coverage surface:1026 \
  --metric water-level \
  --data-type operational

Useful metric aliases:

• water-level
• discharge
• water-temperature

Useful data-type aliases:

• raw
• observed
• checked
• processed
• hydrological
• operational

Numeric VRA codes and exact catalogue names are also accepted.

3. Explain before fetching

uv run vizugy observations get surface:1026 \
  --metric water-level \
  --data-type operational \
  --start 2026-07-16T00:00:00Z \
  --end 2026-07-17T00:00:00Z \
  --explain

The explanation shows the resolved station, metric and data-type codes, UTC bounds, upstream operation, expected mode, and safety warnings. It performs no value query.

4. Retrieve a bounded raw series

uv run vizugy observations get surface:1026 \
  --metric water-level \
  --data-type operational \
  --start 2026-07-16T00:00:00Z \
  --end 2026-07-17T00:00:00Z \
  --limit 1000 \
  --format jsonl

Raw observation queries require explicit bounds and may span at most seven days. JSONL emits one compact timestamp/value record per line followed by a _meta record.

5. Aggregate longer periods upstream

uv run vizugy observations aggregate surface:2046 \
  --metric water-level \
  --data-type operational \
  --start 2026-06-01T00:00:00Z \
  --end 2026-07-01T00:00:00Z \
  --interval daily \
  --operation max

Intervals: daily, tenday, monthly, yearly.

Operations supported by VRAQuery: min, max, avg, sum, cnt, mean, cntday.

Aggregation buckets follow upstream hydrological/local-day boundaries. Returned bucket labels remain UTC timestamps and can precede the requested UTC boundary by an offset.

Dataset discovery

Search the OVF ArcGIS catalogue without knowing folder or layer identifiers:

uv run vizugy datasets list --query Vizmercek --limit 20 --format json

Inspect one service or layer:

uv run vizugy datasets describe \
  VIR/Vizmercek_vizugyhu_orszagos_adatsoros \
  --layer 6

Some advertised ArcGIS folders require authentication. Public discovery skips them and returns explicit warnings rather than failing the entire catalogue request.

CLI reference

vizugy datasets list
vizugy datasets describe
vizugy catalog measurements
vizugy stations search
vizugy stations nearest
vizugy observations coverage
vizugy observations get
vizugy observations aggregate

Machine-readable output goes to stdout; diagnostics go to stderr.

Exit code	Meaning
0	Success
2	Invalid or unsafe query
3	Upstream unavailable or invalid response
4	Requested entity not found

MCP server

Start the local stdio server:

uv run ovf-data-mcp

Example client configuration:

{
  "mcpServers": {
    "vizugy": {
      "command": "uvx",
      "args": ["ovf-data-mcp"]
    }
  }
}

Available tools:

Tool	Intent
discover_datasets	Search public spatial datasets
describe_dataset	Inspect a service or layer schema
list_measurement_types	Resolve metrics, units, ranges, and data types
find_stations	Resolve station names, rivers, and municipalities
nearest_stations	Resolve coordinates to nearby stations
inspect_coverage	Check temporal availability before querying
get_observations	Retrieve a bounded raw series
aggregate_observations	Aggregate a longer series upstream

Output semantics

Observation results distinguish:

• station identity and location;
• observation or aggregation-bucket timestamp;
• metric and unit;
• VRA data type;
• requested UTC interval;
• retrieval timestamp;
• provider and source operation;
• truncation and upstream warnings.

The coverage endpoint currently omits composed operational type 101. When related type 100 coverage exists, vizugy returns it with an explicit inference warning; it does not silently claim equivalence.

Configuration

Variable	Default	Purpose
VIZUGY_ARCGIS_URL	https://geoportal.vizugy.hu/arcgis/rest	ArcGIS catalogue root
VIZUGY_VRA_URL	https://vmservice.vizugy.hu/vraquery	VRAQuery API root
VIZUGY_TOKEN_URL	https://data.vizugy.hu/AuthApi/auth/token	Public frontend token endpoint
VIZUGY_TIMEOUT_SECONDS	15	Upstream request timeout
VIZUGY_CACHE_TTL_SECONDS	300	ArcGIS metadata cache lifetime

Development

uv sync --extra test
uv run ruff format --check src tests
uv run ruff check src tests
uv run ty check src tests
uv run pytest -q

Design decisions, verified upstream behavior, and unresolved questions are documented in docs/design.md and docs/phase-2-review.md.

Licence and data attribution

The software licence has not yet been finalized in this repository. Public endpoint access alone does not establish unrestricted reuse rights for every upstream dataset. Preserve OVF provenance and verify the applicable terms before redistribution or production use.