Lex: Luxembourg Law MCP Server

search

Filtered legal search. keyword is deterministic FTS5/BM25; hybrid adds the pinned local encoder and fixed RRF when verified vectors are mounted. No generative model participates. The response query_plan separates resolved work constraints, article and role intent, and residual provision terms. Returns hits WITHOUT body text; full state via as_of.

Input Schema

TableJSON Schema

Name	Required	Description
`as_of`	No	ISO date required when time_scope=as_of
`fuzzy`	No	auto or off; visible fallback only
`limit`	No	default 10; minimum 1, maximum 50
`query`	Yes	search terms
`works`	No	optional comma-separated work ids: restrict search to these works
`domain`	No	legacy domain id filter; current v4 indexes leave it empty; use publisher_metadata_identifier for official classifications
`act_form`	No	optional legal act form
`language`	No	optional language code
`hierarchy`	No	optional normalized legal hierarchy
`publisher`	No	optional publisher id
`time_scope`	No	all_versions or as_of
`jurisdiction`	No	optional jurisdiction code from index metadata, e.g. LU or EU
`source_class`	No	optional source document class
`document_type`	No	backward-compatible document type filter
`binding_status`	No	optional binding status
`retrieval_mode`	No	keyword or hybrid; default keyword until activation
`publisher_metadata_identifier`	No	optional exact official publisher-metadata URI returned by a search hit

Schema Changelog

Changes observed during successful MCP inspections.

Changed4 schema fields changedAug 17, 2026

addedInput schema / allOf

Added value: +[
+  {
+    "if": {
+      "properties": {
+        "time_scope": {
+          "const": "as_of"
+        }
+      },
+      "required": [
+        "time_scope"
+      ]
+    },
+    "then": {
+      "required": [
+        "as_of"
+      ]
+    }
+  }
+]

changedInput schema / properties / as_of / pattern

Previous value: -"^[0-9]{4}-[0-9]{2}-[0-9]{2}$"New value: +"^\\d{4}-(0[1-9]|1[0-2])-(0[1-9]|[12][0-9]|3[01])$"

changedInput schema / properties / domain / description

Previous value: -"optional reviewed legal domain id"New value: +"legacy domain id filter; current v4 indexes leave it empty; use publisher_metadata_identifier for official classifications"

addedInput schema / properties / publisher_metadata_identifier

Added value: +{
+  "description": "optional exact official publisher-metadata URI returned by a search hit",
+  "maxLength": 2048,
+  "minLength": 1,
+  "pattern": "^https?://",
+  "type": "string"
+}

Changed35 schema fields changedAug 11, 2026
- addedInput schema / additionalProperties
```
Added value: +false
```
- addedInput schema / properties / act_form / maxLength
```
Added value: +1000
```
- addedInput schema / properties / act_form / minLength
```
Added value: +1
```
- addedInput schema / properties / as_of / maxLength
```
Added value: +10
```
- addedInput schema / properties / as_of / minLength
```
Added value: +1
```
- addedInput schema / properties / as_of / pattern
```
Added value: +"^[0-9]{4}-[0-9]{2}-[0-9]{2}$"
```
- addedInput schema / properties / binding_status / maxLength
```
Added value: +1000
```
- addedInput schema / properties / binding_status / minLength
```
Added value: +1
```
- addedInput schema / properties / document_type / maxLength
```
Added value: +1000
```
- addedInput schema / properties / document_type / minLength
```
Added value: +1
```
- addedInput schema / properties / domain / maxLength
```
Added value: +1000
```
- addedInput schema / properties / domain / minLength
```
Added value: +1
```
- addedInput schema / properties / fuzzy / enum
```
Added value: +[
+  "auto",
+  "off"
+]
```
- addedInput schema / properties / fuzzy / maxLength
```
Added value: +64
```
- addedInput schema / properties / fuzzy / minLength
```
Added value: +1
```
- addedInput schema / properties / hierarchy / maxLength
```
Added value: +1000
```
- addedInput schema / properties / hierarchy / minLength
```
Added value: +1
```
- addedInput schema / properties / jurisdiction / maxLength
```
Added value: +64
```
- addedInput schema / properties / jurisdiction / minLength
```
Added value: +1
```
- addedInput schema / properties / language / maxLength
```
Added value: +16
```
- addedInput schema / properties / language / minLength
```
Added value: +1
```
- addedInput schema / properties / publisher / maxLength
```
Added value: +64
```
- addedInput schema / properties / publisher / minLength
```
Added value: +1
```
- addedInput schema / properties / query / maxLength
```
Added value: +1000
```
- addedInput schema / properties / query / minLength
```
Added value: +1
```
- addedInput schema / properties / retrieval_mode / enum
```
Added value: +[
+  "keyword",
+  "hybrid"
+]
```
- addedInput schema / properties / retrieval_mode / maxLength
```
Added value: +64
```
- addedInput schema / properties / retrieval_mode / minLength
```
Added value: +1
```
- addedInput schema / properties / source_class / maxLength
```
Added value: +1000
```
- addedInput schema / properties / source_class / minLength
```
Added value: +1
```
- addedInput schema / properties / time_scope / enum
```
Added value: +[
+  "all_versions",
+  "as_of"
+]
```
- addedInput schema / properties / time_scope / maxLength
```
Added value: +64
```
- addedInput schema / properties / time_scope / minLength
```
Added value: +1
```
- addedInput schema / properties / works / maxLength
```
Added value: +1000
```
- addedInput schema / properties / works / minLength
```
Added value: +1
```
Changed3 schema fields changedAug 9, 2026
- changedInput schema / properties / limit / description
```
Previous value: -"default 10"New value: +"default 10; minimum 1, maximum 50"
```
- addedInput schema / properties / limit / maximum
```
Added value: +50
```
- addedInput schema / properties / limit / minimum
```
Added value: +1
```

Changed1 schema field changedAug 7, 2026

changedInput schema / properties / domain / description

Previous value: -"optional reviewed EU domain id"New value: +"optional reviewed legal domain id"

Changed1 schema field changedAug 7, 2026

changedInput schema / properties / jurisdiction / description

Previous value: -"optional lu or eu"New value: +"optional jurisdiction code from index metadata, e.g. LU or EU"

Changed13 schema fields changedAug 6, 2026

addedInput schema / properties / act_form

Added value: +{
+  "description": "optional legal act form",
+  "type": "string"
+}

changedInput schema / properties / as_of / description

Previous value: -"optional ISO date: only versions valid on this date"New value: +"ISO date required when time_scope=as_of"

addedInput schema / properties / binding_status

Added value: +{
+  "description": "optional binding status",
+  "type": "string"
+}

changedInput schema / properties / document_type / description

Previous value: -"optional type code"New value: +"backward-compatible document type filter"

addedInput schema / properties / domain

Added value: +{
+  "description": "optional reviewed EU domain id",
+  "type": "string"
+}

addedInput schema / properties / fuzzy

Added value: +{
+  "description": "auto or off; visible fallback only",
+  "type": "string"
+}

addedInput schema / properties / hierarchy

Added value: +{
+  "description": "optional normalized legal hierarchy",
+  "type": "string"
+}

addedInput schema / properties / jurisdiction

Added value: +{
+  "description": "optional lu or eu",
+  "type": "string"
+}

addedInput schema / properties / language

Added value: +{
+  "description": "optional language code",
+  "type": "string"
+}

addedInput schema / properties / retrieval_mode

Added value: +{
+  "description": "keyword or hybrid; default keyword until activation",
+  "type": "string"
+}

addedInput schema / properties / source_class

Added value: +{
+  "description": "optional source document class",
+  "type": "string"
+}

addedInput schema / properties / time_scope

Added value: +{
+  "description": "all_versions or as_of",
+  "type": "string"
+}

changedInput schema / properties / works / description

Previous value: -"optional comma-separated work ids: restrict the search to these works, for callers that know their subject"New value: +"optional comma-separated work ids: restrict search to these works"

First observedAug 5, 2026

TDQS

A4/5.0

Behavior4/5

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

With no annotations, the description carries the transparency burden and does well: it discloses deterministic FTS5/BM25, conditional hybrid behavior, the absence of a generative model, the query_plan structure, and the lack of body text in results. It does not cover authentication or rate limits, but that is reasonable for a search tool.

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 dense, purposeful sentences that front-load the core purpose ('Filtered legal search') and then provide only high-value clarifications. No redundant or filler content.

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 the tool's complexity (17 params, conditional validation, no output schema), the description covers key aspects: retrieval modes, output characteristics, and the as_of state mechanism. Minor gaps like error handling and result ordering are not fatal because the schema fills in parameter constraints.

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

Parameters3/5

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

All 17 parameters already have schema descriptions, so the description adds minimal per-parameter semantics. It adds useful context about retrieval_mode and the query_plan, but does not go deeper than the schema for individual parameters.

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 identifies a filtered legal search tool, noting its deterministic and hybrid retrieval modes and stating that no generative model participates. It distinguishes itself from sibling tools by detailing the query_plan output and the explicit absence of body text in hits.

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 explains when hybrid mode is used versus keyword mode and hints at vector availability, but it does not explicitly address when to use this tool over siblings like article_history or cited_by. Usage context is implied rather than directly stated.

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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