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malkreide

swiss-housing-mcp

by malkreide

swiss-housing-mcp

Part of the Swiss Public Data MCP Portfolio — open-source MCP servers connecting AI agents to Swiss public data. Private project, independent of any employer or institutional affiliation.

Version License: MIT Python MCP

MCP server for the Swiss Federal Register of Buildings and Dwellings (GWR/RegBL) — buildings, dwellings, and the construction pipeline

🇩🇪 Deutsche Version


🎯 Anchor Demo Query

«How many dwellings were newly built in the City of Zurich since 2020, how many with 4+ rooms — and how many are currently under construction?»

Verified against the live dump on 2026-07-24: 16'164 new dwellings since 2020 (27.4% with 4+ rooms — the family-housing proxy), and 7'287 dwellings currently under construction. Dwellings under construction today are households in 1–3 years: the early indicator for school-space planning.

Demo

Demo: Claude using new_construction and construction_pipeline


Related MCP server: swiss-statistics-mcp

Overview

The GWR/RegBL is to buildings what Zefix is to companies: not one data source among many, but the federal register whose identifiers (EGID for buildings, EWID for dwellings) serve as join keys across Swiss administrative data. This server exposes the register's public extract through MCP tools — building lookups, address geocoding, per-municipality construction statistics, sub-municipal bounding-box analysis, and the planning/construction pipeline.

address_to_egid is the plug that makes other data sources EGID-capable: address in, federal identifier and LV95 coordinates out.

Architecture decision

This server uses Architecture B (Hybrid: Dump-first, API-fallback).

Rationale (verified live on 2026-07-24):

  • The public cantonal dump (public.madd.bfs.admin.ch/{canton}.zip) is refreshed daily (~05:30 CET) and ships a ready-made data.sqlite with tables building (399'830 rows for ZH), entrance, dwelling (894'631 rows for ZH), and code. No CSV parsing, no auth.

  • api3.geo.admin.ch (find / identify / SearchServer) works reliably without authentication for single-entity lookups and geocoding, but does not scale to area-wide aggregations (result limits).

  • A MADD REST endpoint probed at /api/buildings/{egid} returned 404; it is excluded until path and auth status are clarified — no blocker, since all Phase-1 tools work without it.

Consequences:

  • Cantonal dumps are cached on disk with a 24 h TTL (configurable via SWISS_HOUSING_DUMP_TTL_HOURS).

  • Aggregations and spatial queries run as read-only SQL against the cached SQLite; single lookups and geocoding hit the live API.

  • Every response carries source (attribution) and provenance (daily_dump | live_api | cached).

Live probe findings (2026-07-24)

Endpoint

HTTP

Status

Note

api3.geo.admin.ch …/find (EGID lookup)

200

✅ works

full attribute set, no auth

api3.geo.admin.ch …/identify (coordinates)

200

✅ works

77 attributes incl. EGID/EWID

…/SearchServer (address → EGID)

200

✅ works

featureId = {EGID}_{EDID}; axis swap: y=east, x=north

public.madd.bfs.admin.ch/zh.zip

200

✅ works

121 MB, daily refresh, contains data.sqlite

madd.bfs.admin.ch/api/buildings/{egid}

404

❌ excluded

path/auth unclear

Invalid EGID on find

200

⚠️ soft error

empty results array — not an HTTP error

Features

  • lookup_building(egid) — single building by federal identifier (live API)

  • address_to_egid(address) — geocode any Swiss address to EGID/EDID + LV95

  • lookup_dwellings(egid) — all dwellings of a building with rooms, area, floor

  • new_construction(municipality_bfs, since_year) — yearly new construction incl. 4+ room family-housing share

  • construction_pipeline(municipality_bfs) — projected / approved / under construction

  • buildings_in_bbox(e_min, n_min, e_max, n_max) — sub-municipal analysis (e.g. school districts)

  • municipality_housing_stats(municipality_bfs) — housing stock and room-size mix

  • explain_code(attribute, code) — decode GWR codes via the official DE/FR/IT code table

  • dump_status() — cache freshness, graceful-degradation entry point

Prerequisites

  • Python 3.10+

  • ~130 MB disk per cached cantonal dump (ZH)

  • No API keys — Phase 1 is authentication-free

Installation

uvx swiss-housing-mcp        # once published on PyPI

# or from source
pip install -e .

Usage / Quickstart

Claude Desktop (claude_desktop_config.json):

{
  "mcpServers": {
    "swiss-housing": {
      "command": "uvx",
      "args": ["swiss-housing-mcp"]
    }
  }
}

Cloud (Render/Railway):

SWISS_HOUSING_TRANSPORT=streamable-http PORT=8000 swiss-housing-mcp

Configuration

Variable

Default

Purpose

SWISS_HOUSING_TRANSPORT

stdio

stdio | streamable-http | sse

SWISS_HOUSING_CACHE

~/.cache/swiss-housing-mcp

Dump cache directory

SWISS_HOUSING_DUMP_TTL_HOURS

24

Dump freshness window

MCP Protocol Version

This server speaks two protocol eras over the same endpoint. The client's first request on a connection decides which one applies; a later claim from the other era is refused.

Era

Revision

Who reaches it

initialize handshake

2024-11-052025-11-25

What today's clients speak. The server answers with the revision asked for, or with the 2025-11-25 ceiling when the request asks for something newer.

Per-request envelope

2026-07-28

A request carrying the 2026-07-28 _meta envelope opens a modern connection.

Both revisions are pinned in tests/test_protocol_version.py and asserted against the installed SDK, so a Dependabot bump of mcp cannot move either one silently. This server builds no ASGI app to send an initialize through, so the gate asserts the SDK constants rather than a measured response — the weaker form, named rather than left unsaid.

Note that the SDK's LATEST_PROTOCOL_VERSION is an alias for the modern era, not for the handshake era — pinning against it alone would leave the era that current clients actually negotiate free to drift.

Update policy. When the gate fails, do not edit the constant blindly: read the spec changelog between the two revisions, verify the server still behaves, then move the constant, this section, README.de.md and CHANGELOG.md together.

Testing

PYTHONPATH=src pytest tests/ -m "not live"   # CI-safe
PYTHONPATH=src pytest tests/ -m live         # against real upstream

Project Structure

swiss-housing-mcp/
├── src/swiss_housing_mcp/
│   ├── server.py      # FastMCP tools (9)
│   ├── gwr.py         # Dump store + geo.admin.ch client + retry
│   ├── models.py      # Pydantic v2 envelopes (source + provenance)
│   └── __main__.py    # Dual-transport entry point
├── tests/             # respx-mocked + @pytest.mark.live
└── .github/workflows/ # CI + OIDC PyPI publish

Known Limitations

  • The public extract omits person-related and some sensitive attributes of the full GWR; official data deliveries to authorities go through the BFS/MADD channel.

  • Coordinates are building reference points (LV95), not footprint polygons — polygon joins (e.g. exact school-district boundaries) need external geometries; buildings_in_bbox covers the rectangular approximation.

  • GBAUJ (construction year) is missing for a share of older buildings; period codes (GBAUP) exist as fallback but are not yet exposed.

  • Municipality→canton resolution is seeded for common cases; pass canton explicitly for others.

  • Housing-market indices (IMPI, construction price index, vacancy rate) deliberately live in swiss-statistics-mcp — this server is the register layer, not the statistics layer.

Changelog

See CHANGELOG.md

Contributing

Contributions are welcome — see CONTRIBUTING.md (Deutsch).

Security

Read-only, no PII, no authentication — a public federal register accessed through a fixed set of endpoints. See SECURITY.md (Deutsch) for the full posture and how to report a vulnerability.

License

MIT License — see LICENSE. Data: GWR/RegBL, Swiss Federal Statistical Office (BFS), open government data with attribution.

Author

Hayal Oezkan · github.com/malkreide

Available Tools

5 tools
construction_pipelineB
Read-only

Buildings and dwellings in the planning/construction pipeline of a municipality.

Breaks down by status: projected (GSTAT 1001), approved (1002), under construction (1003). Dwellings under construction today are households in 1-3 years — the early indicator for school-space planning.

ParametersJSON Schema
NameRequiredDescriptionDefault
cantonNo
municipality_bfsYes

Output Schema

ParametersJSON Schema
NameRequiredDescription
noteNo
sourceNo
pipelineYes
provenanceYes
municipalityYes
municipality_bfsYes

TDQS

B3.4/5.0
Behavior3/5

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

Annotations already declare readOnlyHint=true, so the description's additional information about status breakdowns and the interpretation of 'under construction' as an early indicator adds useful behavioral context. However, it does not disclose potential limitations like data availability by municipality or time-range constraints.

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 three concise sentences: the first states the core purpose, the second details the status categories, and the third explains the practical implication. Every sentence adds value, and the content is front-loaded with the most critical information.

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

Completeness3/5

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

Given the presence of an output schema and the tool's moderate complexity, the description covers the data meaning and use case. However, it omits parameter semantics and does not specify what the output contains or how to interpret the status codes fully (though codes are listed). The description is adequate but not comprehensive.

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

Parameters1/5

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

The input schema has 0% description coverage for its two parameters (canton, municipality_bfs). The description does not mention these parameters or provide any guidance on their values, formats, or roles. With no schema descriptions and no parameter information in the description, the agent receives no help beyond the schema structure.

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 specifies the tool retrieves buildings and dwellings in the planning/construction pipeline of a municipality, with explicit breakdowns by status codes. This verb-resource combination is distinct from sibling tools like lookup_dwellings (likely existing dwelling data) and new_construction (new building registrations). The context of early indicator for school-space planning further differentiates its use case.

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

Usage Guidelines3/5

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

The description implies usage for getting pipeline data for a municipality and hints at its value for school-space planning, but it does not explicitly state when to prefer this tool over siblings or when not to use it. No exclusions or alternative recommendations are provided.

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

dump_statusA
Read-only

Cache status of the cantonal GWR dumps (graceful-degradation entry point).

Always returns an evaluable status — never silently empty records. If a source is unreachable, this tool tells you when data was last refreshed.

ParametersJSON Schema
NameRequiredDescriptionDefault

No parameters

Output Schema

ParametersJSON Schema
NameRequiredDescription
noteYes
dumpsYes
sourceNo
ttl_hoursYes
provenanceYes

TDQS

A3.9/5.0
Behavior4/5

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

Annotations already declare readOnlyHint=true. The description adds value by stating the tool never returns empty records and reports last refresh time, which is beyond what annotations provide. No contradictions.

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?

Two sentences, no wasted words. The key information is front-loaded and every sentence contributes meaning.

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 zero parameters and the existence of an output schema, the description adequately covers the tool's behavior and return value. It is sufficient for the agent to understand what to expect, though it doesn't detail the output structure.

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?

No parameters exist, so the baseline is 4. The description correctly adds no parameter information since none are needed.

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

Purpose4/5

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

The description clearly states the tool shows cache status of GWR dumps with graceful degradation. It is distinct from sibling tools like lookup_dwellings which retrieve data. No explicit differentiation from siblings, but the purpose is clear.

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

Usage Guidelines3/5

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

The description implies usage for checking cache health even when sources are unreachable, but does not explicitly state when to use it over alternatives. It provides context but no exclusions or direct guidance.

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

explain_codeA
Read-only

Decode a GWR code value (e.g. GSTAT=1004, GKAT=1020) into human-readable labels.

Uses the official code table shipped with the dump (DE/FR/IT).

ParametersJSON Schema
NameRequiredDescriptionDefault
codeYes
cantonNozh
attributeYes

Output Schema

ParametersJSON Schema
NameRequiredDescription
sourceNo
provenanceYes
explanationsYes

TDQS

A3.7/5.0
Behavior4/5

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

Annotations already declare readOnlyHint=true, so the read-only nature is clear. The description adds value by specifying the source of the labels (official code table) and the supported languages (DE/FR/IT), going beyond what annotations provide.

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 very concise at two sentences, but the second sentence could be more structured or broken into bullet points for clarity. No superfluous information, but room for slight improvement.

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

Completeness3/5

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

Given the tool's moderate complexity (3 params, no enums) and the presence of an output schema, the description adequately covers the main purpose. However, it lacks explanation for the optional parameter and does not mention the output schema's structure, resulting in moderate completeness.

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

Parameters2/5

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

With 0% schema description coverage, the description bears the full burden of explaining parameters. It includes an example of 'attribute' and 'code' but does not describe the optional 'canton' parameter at all, leaving a gap in understanding.

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 decodes GWR code values into human-readable labels, with a specific verb and resource. It provides an example of inputs (GSTAT=1004) and distinguishes itself from sibling tools that handle different tasks.

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

Usage Guidelines3/5

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

The description implies use for decoding codes from a specific code table, but does not explicitly state when to use this tool vs alternatives, nor does it mention any prerequisites or when not to use it. Sibling tools have different purposes, so some implicit differentiation exists.

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

lookup_dwellingsA
Read-only

List all dwellings (EWID) of a building from the daily cantonal dump.

Includes rooms, floor area, floor and status per dwelling.

ParametersJSON Schema
NameRequiredDescriptionDefault
egidYes
cantonNozh

Output Schema

ParametersJSON Schema
NameRequiredDescription
egidYes
countYes
sourceNo
dwellingsYes
provenanceYes

TDQS

A3.5/5.0
Behavior3/5

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

Annotations already declare readOnlyHint=true. The description adds context (data source 'daily cantonal dump' and included fields) but does not disclose behavior beyond that, such as error handling or permissions. No contradiction with 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 concise (two sentences) and front-loaded with the core action. However, it could be slightly more structured with bullet points for clarity.

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

Completeness3/5

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

For a read-only list tool with an output schema, the description adequately mentions included fields but omits explanation of the required 'egid' parameter and the default value for 'canton'. The data source reference is vague.

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

Parameters2/5

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

Schema description coverage is 0%, so the description should explain parameters. However, it does not mention 'egid' as building ID or 'canton''s role. It only references 'a building' implicitly, leaving parameter semantics unclear.

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 all dwellings (EWID) of a building' and specifies included attributes (rooms, floor area, floor, status). This distinguishes it from sibling tools like new_construction or dump_status.

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

Usage Guidelines3/5

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

Usage is implied but not explicit. The description does not mention when to use this tool versus alternatives, nor does it provide conditions for appropriate use.

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

new_constructionB
Read-only

New residential construction per year for a municipality (existing buildings).

Returns buildings, dwellings and 4+ room dwellings per year — the 4+ room share is a proxy for family housing and thus for future pupil numbers. Municipality is identified by its BFS number (e.g. 261 = City of Zurich).

ParametersJSON Schema
NameRequiredDescriptionDefault
cantonNo
since_yearNo
municipality_bfsYes

Output Schema

ParametersJSON Schema
NameRequiredDescription
sourceNo
per_yearYes
provenanceYes
since_yearYes
municipalityYes
total_dwellingsYes
family_share_pctYesShare of 4+ room dwellings — proxy for family housing
municipality_bfsYes
total_dwellings_4plus_roomsYes

TDQS

B3/5.0
Behavior3/5

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

Annotations already indicate readOnlyHint=true. Description adds context about the 4+ room share being a proxy for family housing, but does not disclose any additional behavioral traits such as data source, update frequency, or limitations.

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?

Description is two sentences, efficiently conveying core purpose and a key interpretation note. No redundancy or fluff.

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

Completeness3/5

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

With an output schema present, return value explanation is not needed. However, the description lacks usage context and does not fully cover parameters. Adequate but with gaps.

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

Parameters2/5

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

Schema description coverage is 0%. Description only explains municipality_bfs with an example. Parameters canton and since_year are not described at all, leaving their semantics unclear.

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

Purpose4/5

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

Description clearly states it returns annual new residential construction data for a municipality, including buildings, dwellings, and 4+ room dwellings. However, phrasing 'existing buildings' may cause confusion about whether it covers new construction or existing stock.

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

Usage Guidelines2/5

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

No guidance on when to use this tool versus siblings like lookup_dwellings or construction_pipeline. Does not mention alternatives or exclusions.

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. 5 tool updatesv0.1.0
    • First observedconstruction_pipeline
    • First observeddump_status
    • First observedexplain_code
    • First observedlookup_dwellings
    • First observednew_construction

TDQS

A3.6/5.0

Scored across 5 tools

Disambiguation5/5

Each tool targets a distinct aspect: listing dwellings, historical construction, pipeline, code explanation, and cache status. There is no overlap or ambiguity in their purposes.

Naming Consistency3/5

Tool names mix patterns: verb_noun (lookup_dwellings, explain_code), adjective_noun (new_construction), and noun_noun (construction_pipeline, dump_status). While readable, the lack of a uniform pattern reduces consistency.

Tool Count5/5

Five tools is well-scoped for a niche domain like Swiss housing data. Each tool serves a clear function without excess or deficiency.

Completeness4/5

The tools cover current dwelling data, historical construction, future pipeline, code decoding, and system status. A minor gap is the lack of a dedicated building-level query beyond dwellings, but the set supports the stated planning use case.

Maintenance

ActivityActive
ResponsivenessNo issues

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