UK Legal Research

Resolve Single OSCOLA Citation

citations_resolve

Read-onlyIdempotent

USE THIS TOOL BEFORE constructing an OSCOLA citation string from known fields, OR to confirm a citation points at a real document.

Parses + resolves a single citation (neutral citation, SI, legislation section, retained EU law) and returns parsed fields plus resolved_url. For neutral citations, performs a live TNA HEAD check — non-200 sets confidence to 0.0 (document absent). Do NOT format or quote a confidence-0.0 citation.

If the TNA HEAD check fails (timeout, connection error), raises ToolError with {"error_category": "transient", "is_retryable": true}. One retry is attempted — retry this call or proceed without TNA verification.

Formatting a citation from "known" fields without prior resolution is the most common fabrication route. If this tool raises or returns no resolved_url, do NOT manufacture a citation — surface the failure and ask the user for the source URL.

Authoritative source for UK legal-citation resolution.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`citation`	Yes	A single OSCOLA citation to parse and resolve. E.g. '[2024] UKSC 12', 'SI 2018/1234', 's.47 Companies Act 2006'

Output Schema

TableJSON Schema

Name	Required	Description
`raw`	Yes	Original citation text as found in the source
`page`	No	Starting page in the law report
`type`	Yes	Classification of the citation type
`year`	No	Year component of the citation
`court`	No	Court code: UKSC, UKPC, EWCA Civ, EWCA Crim, EWHC (KB), EWHC (Ch), EWHC (Comm), EWHC (Fam), EWHC (Pat), EWHC (IPEC), UKUT (IAC), UKUT (TCC), UKUT (AAC), UKUT (LC), EAT, UKFTT (TC), UKFTT (GRC)
`number`	No	Judgment number within the year
`volume`	No	Report volume number (for law reports)
`section`	No	Section number referenced
`si_year`	No	SI year (for SI YYYY/NNN citations)
`si_number`	No	SI number
`confidence`	Yes	Parse confidence 0.0–1.0. Citations below 0.7 are ambiguous and may have been sent for LLM disambiguation.
`resolved_url`	No	TNA Find Case Law or legislation.gov.uk URL if successfully resolved
`report_series`	No	Law report series abbreviation: WLR, AC, QB, KB, Ch, All ER, EWCA Civ, etc.
`legislation_title`	No	Title of legislation (for s.NN Act YYYY citations)

Schema Changelog

Changes observed during successful MCP inspections.

Changed3 schema fields changedJun 14, 2026

addedInput schema / properties / citation

Added value: +{
+  "description": "A single OSCOLA citation to parse and resolve. E.g. '[2024] UKSC 12', 'SI 2018/1234', 's.47 Companies Act 2006'",
+  "maxLength": 500,
+  "minLength": 3,
+  "type": "string"
+}

removedInput schema / properties / params

Removed value: -{
-  "additionalProperties": false,
-  "description": "CitationsResolveInput.",
-  "properties": {
-    "citation": {
-      "description": "A single OSCOLA citation to parse and resolve. E.g. '[2024] UKSC 12', 'SI 2018/1234', 's.47 Companies Act 2006'",
-      "maxLength": 500,
-      "minLength": 3,
-      "type": "string"
-    }
-  },
-  "required": [
-    "citation"
-  ],
-  "type": "object"
-}

changedInput schema / required

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

Changed1 schema field changedMay 30, 2026

changedInput schema / properties / params / description

Previous value: -"CitationsResolveInput with a single citation string."New value: +"CitationsResolveInput."

Changed1 schema field changedApr 20, 2026
- addedInput schema / properties / params / description
```
Added value: +"CitationsResolveInput with a single citation string."
```

Changed18 schema fields changedApr 15, 2026

changedOutput schema / description

Previous value: -"Generic wrapper for non-object return types."New value: +"A single parsed OSCOLA citation with optional resolution."

addedOutput schema / properties / confidence

Added value: +{
+  "description": "Parse confidence 0.0–1.0. Citations below 0.7 are ambiguous and may have been sent for LLM disambiguation.",
+  "maximum": 1,
+  "minimum": 0,
+  "type": "number"
+}

addedOutput schema / properties / court

Added value: +{
+  "anyOf": [
+    {
+      "type": "string"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "default": null,
+  "description": "Court code: UKSC, UKPC, EWCA Civ, EWCA Crim, EWHC (KB), EWHC (Ch), EWHC (Comm), EWHC (Fam), EWHC (Pat), EWHC (IPEC), UKUT (IAC), UKUT (TCC), UKUT (AAC), UKUT (LC), EAT, UKFTT (TC), UKFTT (GRC)"
+}

addedOutput schema / properties / legislation_title

Added value: +{
+  "anyOf": [
+    {
+      "type": "string"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "default": null,
+  "description": "Title of legislation (for s.NN Act YYYY citations)"
+}

addedOutput schema / properties / number

Added value: +{
+  "anyOf": [
+    {
+      "type": "integer"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "default": null,
+  "description": "Judgment number within the year"
+}

addedOutput schema / properties / page

Added value: +{
+  "anyOf": [
+    {
+      "type": "integer"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "default": null,
+  "description": "Starting page in the law report"
+}

addedOutput schema / properties / raw

Added value: +{
+  "description": "Original citation text as found in the source",
+  "type": "string"
+}

addedOutput schema / properties / report_series

Added value: +{
+  "anyOf": [
+    {
+      "type": "string"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "default": null,
+  "description": "Law report series abbreviation: WLR, AC, QB, KB, Ch, All ER, EWCA Civ, etc."
+}

addedOutput schema / properties / resolved_url

Added value: +{
+  "anyOf": [
+    {
+      "type": "string"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "default": null,
+  "description": "TNA Find Case Law or legislation.gov.uk URL if successfully resolved"
+}

removedOutput schema / properties / result

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

addedOutput schema / properties / section

Added value: +{
+  "anyOf": [
+    {
+      "type": "string"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "default": null,
+  "description": "Section number referenced"
+}

addedOutput schema / properties / si_number

Added value: +{
+  "anyOf": [
+    {
+      "type": "integer"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "default": null,
+  "description": "SI number"
+}

addedOutput schema / properties / si_year

Added value: +{
+  "anyOf": [
+    {
+      "type": "integer"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "default": null,
+  "description": "SI year (for SI YYYY/NNN citations)"
+}

addedOutput schema / properties / type

Added value: +{
+  "description": "Classification of the citation type",
+  "enum": [
+    "neutral",
+    "law_report",
+    "legislation",
+    "si",
+    "eu_retained"
+  ],
+  "type": "string"
+}

addedOutput schema / properties / volume

Added value: +{
+  "anyOf": [
+    {
+      "type": "integer"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "default": null,
+  "description": "Report volume number (for law reports)"
+}

addedOutput schema / properties / year

Added value: +{
+  "anyOf": [
+    {
+      "type": "integer"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "default": null,
+  "description": "Year component of the citation"
+}

changedOutput schema / required

Previous value: -[
-  "result"
-]New value: +[
+  "raw",
+  "type",
+  "confidence"
+]

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

First observedApr 14, 2026

TDQS

A4.9/5.0

Behavior5/5

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

Beyond the annotations, the description reveals live TNA HEAD-check behavior, confidence scores dropping to 0.0 on non-200 responses, and ToolError with retryable semantics. It also warns about quoting low-confidence results, which is important behavioral context for downstream use.

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 well-structured and front-loads the usage directive, but some safety warnings are repeated (e.g., not formatting or quoting unresolved citations). The redundancy is understandable for risk mitigation but prevents a perfect conciseness score.

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 input, output shape, error behavior, retry semantics, and downstream safety considerations. Given the presence of an output schema, the additional context about confidence and resolved_url is sufficient for an agent to use the tool correctly.

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

Parameters5/5

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

The schema fully describes the single required citation parameter with length constraints and concrete examples. The tool description additionally enumerates accepted citation types, making the parameter semantics clear and actionable.

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 that the tool parses and resolves a single OSCOLA citation, returning parsed fields and a resolved_url. It also distinguishes this from sibling tools like citations_parse and citations_format_oscola by emphasizing real-document resolution.

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?

The description explicitly instructs agents to use this tool before constructing an OSCOLA citation string or confirming that a citation points to a real document. It also provides critical guidance about not manufacturing citations when resolution fails, which clearly defines when and how to use the tool.

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

All UK Legal Research tools Inspect

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