Examples

Real examples for the Claude Code skills of the mastr plugin, one per skill: a request, the mastr commands the skill ran, and the answer Claude gave.

Every example ran against the live API on 6 October 2026 with mastr 0.2.0, which checks a filter’s FilterNames and dropdown codes against the category’s columns before sending it. The data changes, so your results will differ; the ids and keys shown work for trying the requests yourself. Long lists are shortened.

To try them, install the CLI and the plugin — see SKILLS.md.

Skills: mastr-filters · mastr-search · mastr-unit

mastr-filters

How do I filter MaStR for battery storage in operation in Brandenburg above 10 MW, biggest first?

mastr filters stromerzeugung --compact > filters.json
jq '.[] | {FilterName, Type}' filters.json
jq '.[] | select(.FilterName=="Bundesland" or .FilterName=="Energieträger" or .FilterName=="Betriebs-Status" or .FilterName=="Speichertechnologie") | {FilterName, codes: [.ListObject[] | "\(.Value)=\(.Name)"]}' filters.json
mastr stromerzeugung --filter "Bundesland~eq~'1400'~and~Energieträger~eq~'2496'" --total
F="Bundesland~eq~'1400'~and~Energieträger~eq~'2496'~and~Betriebs-Status~eq~'35'~and~Speichertechnologie~eq~'524'"
mastr stromerzeugung --filter "$F" --total
mastr stromerzeugung --filter "$F~and~Bruttoleistung der Einheit~gte~'10000'" --total       # exit 2: unknown operator, nothing sent
mastr stromerzeugung --filter "$F~and~Bruttoleistung der Einheit~gt~'10000'" --total
mastr stromerzeugung --page-size 1 --compact | jq '.data[0] | keys'
mastr stromerzeugung --filter "$F~and~Bruttoleistung der Einheit~gt~'10000'" --sort "Bruttoleistung-desc" --page-size 15 --iso-dates --compact

The FilterNames and codes came from mastr filters (Bruttoleistung der Einheit is a number column); the CLI checked each filtered call’s names and codes against the same column list before sending it. The gte probe doesn’t reach the register; the CLI rejects it before any request:

error: option '--filter <spec>' argument 'Bundesland~eq~'1400'~and~Energieträger~eq~'2496'~and~Betriebs-Status~eq~'35'~and~Speichertechnologie~eq~'524'~and~Bruttoleistung der Einheit~gte~'10000'' is invalid. Unknown operator "gte" in condition 5. The operators are eq, neq, sw, ct, nct, ew, null, nn, gt, lt (gt/lt are strict; there is no gte/lte); the register returns 0 rows for any other.

The skill used strict gt. It then read the sort key from one record (Bruttoleistung, not the FilterName) before sorting, so the sorted query returned all 11 rows on the first try.

Battery storage in operation in Brandenburg, > 10 MW, largest first

  FilterName                   op   Value   meaning
  Bundesland                   eq   1400    Brandenburg
  Energieträger                eq   2496    Speicher
  Betriebs-Status              eq   35      In Betrieb
  Speichertechnologie          eq   524     Batterie
  Bruttoleistung der Einheit   gt   10000   kW (number field; gt is strict, there is no gte)

  --filter "Bundesland~eq~'1400'~and~Energieträger~eq~'2496'~and~Betriebs-Status~eq~'35'~and~Speichertechnologie~eq~'524'~and~Bruttoleistung der Einheit~gt~'10000'"
  --sort   "Bruttoleistung-desc"

Check with --total: 95,814 storage units in Brandenburg → 94,210 batteries in operation → 11 above 10 MW
First rows: Big Battery Lausitz 66,000 kW (SEE905930139120, Landkreis Spree-Neiße, 2020-11-19)
            BESS Kahsel 32,200 kW (SEE975222107571, Neuhausen, 2026-07-27)
            BESS Löwenberger Land II 22,500 kW (SEE937755233493, Löwenberger Land, 2026-07-05)

Next step offered: hand the filter to mastr-search for the full 11-row list.

How much offshore wind is in operation in Germany right now, and which wind farms are the biggest?

mastr stromerzeugung --total
mastr stromerzeugung --filter "Energieträger~eq~'2497'" --total
mastr stromerzeugung --filter "Energieträger~eq~'2497'~and~Wind an Land oder auf See~eq~'889'" --total
mastr stromerzeugung --filter "Energieträger~eq~'2497'~and~Wind an Land oder auf See~eq~'889'~and~Betriebs-Status~eq~'35'" --total
mastr stromerzeugung --filter "Energieträger~eq~'2497'~and~Wind an Land oder auf See~eq~'889'~and~Betriebs-Status~eq~'35'" --sort "Bruttoleistung-desc" --page-size 2000 --iso-dates --compact

MaStR can’t sum capacity server-side. With 1,808 matches the skill fetched them all in one page (7.5 MB) and summed Bruttoleistung locally, grouping by WindparkName.

Offshore wind in operation: 1,808 units, 11,493,743 kW gross ≈ 11.5 GW
  North Sea 9.37 GW · Baltic Sea 2.13 GW
  Register context: 9,568,968 generation units, 44,248 wind units, 1,909 offshore (all statuses)

Largest wind farms (48 in total)
  Borkum Riffgrund 3   83 units   958.7 MW   Siemens Gamesa   commissioned 2025-12-03 … 2026-08-17
  EnBW He Dreiht       58 units   870.0 MW   Vestas           2025-11-25 … 2026-09-17
  Windpark Hohe See    71 units   521.9 MW   Siemens          2019
  Baltic Eagle         50 units   476.3 MW   Vestas           2024
  Borkum Riffgrund 2   56 units   464.8 MW   MHI Vestas       2018
  OWP Veja Mate        67 units   422.1 MW   Siemens          2017
  … 42 more

Added in 2026 so far: 130 units, 1,760.3 MW (Borkum Riffgrund 3, EnBW He Dreiht, NC 1, OWP Windanker)
Largest single units: 15,000 kW, e.g. SEE920051579655 (HD A1, EnBW He Dreiht)
Source: © Bundesnetzagentur – Marktstammdatenregister (DL-DE-BY-2.0)

mastr-unit

What does MaStR unit SEE920051579655 tell me?

mastr stromerzeugung --filter "MaStR-Nr. der Einheit~eq~'SEE920051579655'" --iso-dates --compact

One call with total: 1 (plus the column list the CLI checks the FilterName against). The record has 119 fields; the skill read the populated ones. The grid operator’s NetzbetreiberMaStRNummer arrives as an HTML link (<a href="/MaStR/Akteur/…">), so it took the number from NetzbetreiberNamen instead.

HD A1 — offshore wind turbine, EnBW He Dreiht (SEE920051579655)
  Status:        In Betrieb (system status: Aktiviert)
  Capacity:      15,000 kW gross = 15,000 kW net (15 MW)
  Turbine:       Vestas Deutschland GmbH V236-15MW, Horizontalläufer,
                 hub height 144.6 m, rotor diameter 236 m
  Location:      Ausschließliche Wirtschaftszone — "Nordsee; Gebiet nach dem
                 Flächenentwicklungsplan des BSH: N-7"; 54.358732 N, 6.197874 E
  Dates:         commissioned 2026-02-24, registered 2026-02-27, last updated 2026-09-18
  Operator:      EnBW He Dreiht GmbH ＆ Co. KG (ABR912332201010) — a company, not anonymised
  Grid:          TenneT TSO GmbH (SNB970033313272), Höchstspannung, Volleinspeisung
  EEG:           EEG961890773712, tender award BK6-17-001-07
  Permit:        SGE959647687634, Bundesamt für Seeschifffahrt und Hydrographie
Source: © Bundesnetzagentur – Marktstammdatenregister (DL-DE-BY-2.0)

Next steps offered: the rest of the wind farm (--filter "Name des Windparks~eq~'EnBW He Dreiht'"), or the linked EEG record.

View the source on GitHub →