LexAPI MCP

Official

Overview Schema Source Related Servers Discussions Admin

lex_cited_by

Retrieve documents that cite a specific CELEX number, grouped by citation type such as reference, amendment, or repeal. Useful for understanding dependencies and modifications of EU legal acts.

Instructions

Find documents that cite this CELEX (inbound edges). Returns source documents grouped with their edge type (reference, amendment, repeal, implementation, legal-basis, proposal). Use to see who depends on or modifies a given act.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "celexNumber": "<celexNumber>"
    },
    "name": "lex_cited_by"
  }
}

Input Schema

Name	Required	Description
`celexNumber`	Yes
`citationType`	No	Optionally filter to one edge type.
`limit`	No
`offset`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Jun 25, 2026

TDQS

A4.2/5.0

Behavior4/5

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

No annotations are provided, so the description carries full burden. It discloses that the tool returns source documents grouped with edge types and lists the possible edge types. This covers key behaviors for a citation query tool, though it omits details like pagination handling or error states.

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: first defines action and output, second gives usage guidance. Every sentence is essential and the purpose is front-loaded. No wasted words.

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?

No output schema exists, so description must explain return values. It does so by stating 'Returns source documents grouped with their edge type' and listing edge types. Parameters celexNumber and citationType are explained. However, pagination (limit/offset) behavior is only in schema, not description. Overall adequate for the tool's complexity.

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?

Schema description coverage is only 25% (only citationType has a description). The tool description explains celexNumber (the CELEX to find citing docs) and mentions citationType for optional filtering. However, it does not describe limit or offset, relying on schema defaults. With low coverage, the description adds moderate value beyond the schema.

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 finds documents citing a given CELEX (inbound edges) and returns them grouped by edge type. The verb 'Find' and resource 'documents that cite this CELEX' are specific. It distinguishes from siblings like lex_cites (outbound) and lex_citation_network (broader network).

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

Usage Guidelines4/5

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

The description includes a usage hint: 'Use to see who depends on or modifies a given act.' This gives context for appropriate use. It does not explicitly exclude alternatives or mention when not to use, but the purpose is clear enough.

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

Deploy Server