1820.ch – Telefonbuch Schweiz

Search the Swiss directory

search_swiss_directory

Read-onlyIdempotent

Full-text search over the Swiss public phone/business directory (1820.ch). Matches ALL words in query, so a short keyword works best; put any place name in location, not query. For "business type X in place Y", browse_business_category with a category slug is an alternative. Use get_directory_entry for phone numbers and opening hours of a specific result.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`lang`	No	Response language: de, fr, it, or en. Defaults to de.
`limit`	No	Maximum number of results, 1-20.
`query`	Yes	One short keyword: a person's or company name, or ONE business type (e.g. "Müller", "Migros", "Coiffeur"). Every word must match, so no sentences or extra adjectives. Never put a place name here — use location instead.
`location`	No	Locality, postcode, or canton (e.g. "Baden", "5400", "ZH") to narrow the search. Always put a place name here, never in query.
`entry_type`	No	Restrict results to person, business, or all entries.	all

Output Schema

TableJSON Schema

Name	Required	Description	Default
`source`	Yes
`results`	Yes
`retrieved_at`	Yes
`advertising_block_note`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed5 schema fields changedSep 27, 2026

addedInput schema / properties / lang

Added value: +{
+  "description": "Response language: de, fr, it, or en. Defaults to de.",
+  "enum": [
+    "de",
+    "fr",
+    "it",
+    "en"
+  ],
+  "type": "string"
+}

changedInput schema / properties / location / description

Previous value: -"Optional locality, postcode, or canton name to narrow the search."New value: +"Locality, postcode, or canton (e.g. \"Baden\", \"5400\", \"ZH\") to narrow the search. Always put a place name here, never in query."

addedInput schema / properties / location / maxLength
```
Added value: +200
```

changedInput schema / properties / query / description

Previous value: -"Free-text search term: a name, company, or category keyword."New value: +"One short keyword: a person's or company name, or ONE business type (e.g. \"Müller\", \"Migros\", \"Coiffeur\"). Every word must match, so no sentences or extra adjectives. Never put a place name here — use location instead."

addedInput schema / properties / query / maxLength
```
Added value: +200
```

First observedSep 27, 2026

TDQS

A4.7/5.0

Behavior4/5

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

Annotations already cover the safety profile (readOnlyHint=true, idempotentHint=true), so the description correctly focuses on behavior beyond that: the AND-matching semantics of 'matches ALL words' is a genuinely useful disclosure that explains why short keywords succeed. It stops short of describing result ordering or what a truncated/no-match response looks like, which keeps it from a 5.

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?

Three sentences, each load-bearing: purpose/scope first, then query-matching behavior and the query/location split, then alternatives and the deeper-lookup sibling. No restatement of the title and no filler.

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?

An output schema exists, so return values need no explanation. With 100% parameter coverage, annotations carrying the safety profile, and the description covering scope, matching semantics, and sibling routing, nothing an agent needs to call this correctly is missing.

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 coverage is 100%, so the baseline is 3, but the description adds a cross-parameter constraint the schema cannot express: place names belong in location and never in query, plus the AND-matching rule that constrains query construction. That is real added meaning over per-field 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?

States a specific verb and resource ('Full-text search over the Swiss public phone/business directory (1820.ch)') and immediately distinguishes itself from siblings by naming both browse_business_category and get_directory_entry with their respective roles. An agent can route without opening any schema.

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?

Gives explicit when-to-use guidance ('short keyword works best'), a placement rule ('put any place name in location, not query'), and a named alternative with the condition that selects it ('For "business type X in place Y", browse_business_category with a category slug is an alternative'). This is the full when/when-not/alternative triad.

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

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