UK Legal Research

Search HMRC Guidance

hmrc_search_guidance

Read-onlyIdempotent

USE THIS TOOL WHEN discovering HMRC GOV.UK guidance on a topic.

Returns official-search titles, URLs, descriptions, and published dates; descriptions do not establish the contents of a cited page. AFTER calling, use hmrc_get_manual_page when a result is an HMRC internal-manual URL. Source: GOV.UK's HMRC-filtered content search API.

Input Schema

Name	Required	Description	Default
`limit`	No	Maximum guidance results to return (1–25). Passed to the GOV.UK search count param.
`query`	Yes	Search query for HMRC guidance, e.g. 'VAT digital services', 'R&D tax relief SME'

Output Schema

Name	Required	Description
`query`	Yes	The search query that was run
`total`	Yes	Number of guidance documents returned in this call
`results`	No	Matching HMRC guidance pages. Each entry's `summary` is capped per the max_summary_chars input parameter.

Schema Changelog

Changes observed during successful MCP inspections.

Changed4 schema fields changedJun 14, 2026

addedInput schema / properties / limit

Added value: +{
+  "default": 10,
+  "description": "Maximum guidance results to return (1–25). Passed to the GOV.UK search count param.",
+  "maximum": 25,
+  "minimum": 1,
+  "type": "integer"
+}

removedInput schema / properties / params

Removed value: -{
-  "additionalProperties": false,
-  "description": "HMRCGuidanceSearchInput.",
-  "properties": {
-    "limit": {
-      "default": 10,
-      "description": "Maximum guidance results to return (1–25). Passed to the GOV.UK search count param.",
-      "maximum": 25,
-      "minimum": 1,
-      "type": "integer"
-    },
-    "query": {
-      "description": "Search query for HMRC guidance, e.g. 'VAT digital services', 'R&D tax relief SME'",
-      "maxLength": 300,
-      "minLength": 3,
-      "type": "string"
-    }
-  },
-  "required": [
-    "query"
-  ],
-  "type": "object"
-}

addedInput schema / properties / query

Added value: +{
+  "description": "Search query for HMRC guidance, e.g. 'VAT digital services', 'R&D tax relief SME'",
+  "maxLength": 300,
+  "minLength": 3,
+  "type": "string"
+}

changedInput schema / required

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

Changed1 schema field changedJun 13, 2026

addedInput schema / properties / params / properties / limit

Added value: +{
+  "default": 10,
+  "description": "Maximum guidance results to return (1–25). Passed to the GOV.UK search count param.",
+  "maximum": 25,
+  "minimum": 1,
+  "type": "integer"
+}

Changed1 schema field changedMay 30, 2026

changedInput schema / properties / params / description

Previous value: -"HMRCGuidanceSearchInput with query (topic to search)."New value: +"HMRCGuidanceSearchInput."

Changed1 schema field changedApr 20, 2026
- addedInput schema / properties / params / description
```
Added value: +"HMRCGuidanceSearchInput with query (topic to search)."
```

Changed7 schema fields changedApr 15, 2026

changedOutput schema / description

Previous value: -"Generic wrapper for non-object return types."New value: +"Result of an HMRC guidance search on GOV.UK.\n\nWraps the list of matching guidance documents with search metadata so\nthe LLM client sees a real nested object on the wire rather than a\nstringified JSON blob."

addedOutput schema / properties / query

Added value: +{
+  "description": "The search query that was run",
+  "type": "string"
+}

removedOutput schema / properties / result

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

addedOutput schema / properties / results

Added value: +{
+  "description": "Matching HMRC guidance pages. Each entry's `summary` is capped per the max_summary_chars input parameter.",
+  "items": {
+    "description": "A single HMRC guidance document search result.",
+    "properties": {
+      "summary": {
+        "anyOf": [
+          {
+            "type": "string"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": null,
+        "description": "Brief summary of the guidance content"
+      },
+      "title": {
+        "description": "Guidance document title",
+        "type": "string"
+      },
+      "updated": {
+        "anyOf": [
+          {
+            "format": "date",
+            "type": "string"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": null,
+        "description": "Date the guidance was last updated"
+      },
+      "url": {
+        "description": "GOV.UK URL for the guidance",
+        "type": "string"
+      }
+    },
+    "required": [
+      "title",
+      "url"
+    ],
+    "type": "object"
+  },
+  "type": "array"
+}

addedOutput schema / properties / total

Added value: +{
+  "description": "Number of guidance documents returned in this call",
+  "type": "integer"
+}

changedOutput schema / required

Previous value: -[
-  "result"
-]New value: +[
+  "query",
+  "total"
+]

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

First observedApr 14, 2026

TDQS

A4.2/5.0

Behavior4/5

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

Annotations already declare read-only, idempotent, open-world, non-destructive behavior. The description adds real value beyond that: it names the underlying source API and warns that result descriptions 'do not establish the contents of a cited page', which prevents the agent from treating snippets as authoritative. It stops short of noting rate limits or result-ranking behavior.

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?

Front-loaded trigger sentence followed by return shape, caveat, and next-step routing — no filler. The enumeration of returned fields partially duplicates the output schema, which is the only small inefficiency.

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, yet the description still supplies the interpretive caveat about snippet reliability and the cross-tool handoff that no structured field carries. An agent has everything needed to call it correctly and interpret the results.

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 100% — both 'query' and 'limit' are fully documented in the input schema, including bounds and examples. The description adds no parameter-level detail (e.g. query syntax or search-operator support), so the baseline 3 applies.

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 + resource + source ('discovering HMRC GOV.UK guidance on a topic', 'GOV.UK's HMRC-filtered content search API'), which is distinct from legislation_search or parliament_search_hansard siblings. The mention of hmrc_get_manual_page as a follow-up further delimits its role in the HMRC tool cluster.

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?

Opens with an explicit trigger ('USE THIS TOOL WHEN discovering HMRC GOV.UK guidance on a topic') and gives a conditional next step ('use hmrc_get_manual_page when a result is an HMRC internal-manual URL'). It lacks an explicit negative case (e.g. 'do not use for legislation text'), but the usage context is clear.

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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