UK Legal Research

Get Case Citation Network

citations_network

Read-onlyIdempotent

USE THIS TOOL WHEN you have a judgment slug and want to map every citation it makes — cases cited, legislation referenced, SIs, retained EU law.

Fetches the judgment XML from TNA and parses all OSCOLA citations within. Returns citations grouped by type, deduplicated and sorted. AFTER calling, pass any individual citation through citations_resolve to confirm it resolves and to retrieve its canonical URL.

Useful for authority-network analysis (what did this judgment rely on?) and for surfacing the legislative landscape a case sits inside.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`case_uri`	Yes	TNA judgment URI slug, e.g. 'uksc/2024/12' or 'ewca/civ/2023/450'. Use the 'uri' field from case_law_search results — not the full URL. Do not include the 'https://caselaw.nationalarchives.gov.uk/' prefix.

Output Schema

TableJSON Schema

Name	Required	Description
`eu_refs`	No	Retained EU law references, e.g. 'Regulation (EU) 2016/679'
`si_refs`	No	Statutory Instrument references, e.g. 'SI 2018/1234'
`case_uri`	Yes	The judgment URI that was fetched and parsed
`law_report_refs`	No	Law report citations, e.g. '[2020] 1 WLR 100'
`total_citations`	Yes	Sum of all de-duplicated citations across every bucket
`legislation_refs`	No	Legislation section references, e.g. 's.47 Companies Act 2006'
`neutral_citations`	No	Neutral citations referenced, e.g. '[2020] UKSC 14'

Schema Changelog

Changes observed during successful MCP inspections.

Changed3 schema fields changedJun 14, 2026

addedInput schema / properties / case_uri

Added value: +{
+  "description": "TNA judgment URI slug, e.g. 'uksc/2024/12' or 'ewca/civ/2023/450'. Use the 'uri' field from case_law_search results — not the full URL. Do not include the 'https://caselaw.nationalarchives.gov.uk/' prefix.",
+  "minLength": 5,
+  "type": "string"
+}

removedInput schema / properties / params

Removed value: -{
-  "additionalProperties": false,
-  "description": "CitationsNetworkInput with case_uri (TNA slug, e.g. 'uksc/2024/12').",
-  "properties": {
-    "case_uri": {
-      "description": "TNA judgment URI slug, e.g. 'uksc/2024/12' or 'ewca/civ/2023/450'. Use the 'uri' field from case_law_search results — not the full URL. Do not include the 'https://caselaw.nationalarchives.gov.uk/' prefix.",
-      "minLength": 5,
-      "type": "string"
-    }
-  },
-  "required": [
-    "case_uri"
-  ],
-  "type": "object"
-}

changedInput schema / required

Previous value: -[
-  "params"
-]New value: +[
+  "case_uri"
+]

Changed1 schema field changedApr 20, 2026
- addedInput schema / properties / params / description
```
Added value: +"CitationsNetworkInput with case_uri (TNA slug, e.g. 'uksc/2024/12')."
```

Changed11 schema fields changedApr 15, 2026

changedOutput schema / description

Previous value: -"Generic wrapper for non-object return types."New value: +"Citations found within a single judgment, grouped by type.\n\nEach list contains the de-duplicated raw citation text as it appeared\nin the source. To resolve any entry to a URL, pass it through\ncitations_resolve."

addedOutput schema / properties / case_uri

Added value: +{
+  "description": "The judgment URI that was fetched and parsed",
+  "type": "string"
+}

addedOutput schema / properties / eu_refs

Added value: +{
+  "description": "Retained EU law references, e.g. 'Regulation (EU) 2016/679'",
+  "items": {
+    "type": "string"
+  },
+  "type": "array"
+}

addedOutput schema / properties / law_report_refs

Added value: +{
+  "description": "Law report citations, e.g. '[2020] 1 WLR 100'",
+  "items": {
+    "type": "string"
+  },
+  "type": "array"
+}

addedOutput schema / properties / legislation_refs

Added value: +{
+  "description": "Legislation section references, e.g. 's.47 Companies Act 2006'",
+  "items": {
+    "type": "string"
+  },
+  "type": "array"
+}

addedOutput schema / properties / neutral_citations

Added value: +{
+  "description": "Neutral citations referenced, e.g. '[2020] UKSC 14'",
+  "items": {
+    "type": "string"
+  },
+  "type": "array"
+}

removedOutput schema / properties / result

Removed value: -{
-  "type": "string"
-}

addedOutput schema / properties / si_refs

Added value: +{
+  "description": "Statutory Instrument references, e.g. 'SI 2018/1234'",
+  "items": {
+    "type": "string"
+  },
+  "type": "array"
+}

addedOutput schema / properties / total_citations

Added value: +{
+  "description": "Sum of all de-duplicated citations across every bucket",
+  "type": "integer"
+}

changedOutput schema / required

Previous value: -[
-  "result"
-]New value: +[
+  "case_uri",
+  "total_citations"
+]

removedOutput schema / x-fastmcp-wrap-result
```
Removed value: -true
```

First observedApr 14, 2026

TDQS

A4.4/5.0

Behavior4/5

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

Annotations already mark the tool as readOnly/idempotent/non-destructive. The description adds valuable behavior details: fetching judgment XML from TNA, parsing OSCOLA citations, grouping by type, deduplicating, and sorting. It also discloses that the tool does not resolve citations, which is a key behavioral limitation.

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 front-loaded with the usage condition and is organized into three focused paragraphs. All sentences contribute useful context, though the format is slightly more verbose than necessary for the information conveyed.

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?

The description covers the input precondition (judgment slug), what the tool does (parse TNA XML for OSCOLA citations), output characteristics (grouped, deduplicated, sorted), and follow-up action (use citations_resolve). With an output schema present, it is fully complete for this 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?

The schema description for case_uri is thorough (slug format, use 'uri' field, no prefix), providing 100% coverage. The description only reiterates the concept of a 'judgment slug' without adding new parameter-level semantics, so the baseline of 3 is appropriate.

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 maps all citations a judgment makes, including cases, legislation, SIs, and retained EU law. It distinguishes itself from sibling tools by emphasizing the network-wide mapping and integration with citations_resolve.

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?

It explicitly starts with 'USE THIS TOOL WHEN you have a judgment slug and want to map every citation it makes' and directs the user to pass citations through citations_resolve after. This provides clear when-to-use and a follow-up alternative, aligning with the sibling tool's purpose.

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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