who-gho-mcp-server

List GHO Dimension Values

who_list_dimension_values

Read-onlyIdempotent

List valid codes and labels for a WHO GHO dimension type such as COUNTRY, REGION, SEX, WORLDBANKINCOMEGROUP, or AGEGROUP. Use this to discover valid filter values before calling who_query_indicator_data, or to confirm the correct ISO code for a country. Use who_list_dimensions to discover all available dimension type codes. Results are paged in a deterministic order — narrow hierarchical dimensions with parent_code (e.g. the countries in one WHO region), and page the rest with offset.

Input Schema

TableJSON Schema

Name	Required	Description
`limit`	No	Number of values to return per page. Default 100, max 500.
`offset`	No	Zero-based offset into the values for this dimension and filter. Default 0. Read hasMore and nextOffset from the response to continue paging. An offset at or beyond totalCount returns an empty values array, not an error.
`dimension`	Yes	Dimension type code. Use who_list_dimensions to discover all available codes. Common values: COUNTRY, REGION, SEX, WORLDBANKINCOMEGROUP, AGEGROUP.
`parent_code`	No	Restrict results to values under one parent, e.g. dimension="COUNTRY" with parent_code="EUR" for the countries in the WHO European Region. Only hierarchical dimensions carry a parent; a filter that matches nothing returns an empty page, not an error.

Output Schema

TableJSON Schema

Name	Required	Description
`error`	No	Present when the call failed. Absent on success.
`notice`	No	Present when values were withheld, the parent_code filter matched nothing, or the requested offset ran past the end. Explains what to do next.
`offset`	No	Zero-based offset this page started at.
`values`	No	Valid values for this dimension type, for the requested page.
`hasMore`	No	True when more values remain beyond this page. Pair with nextOffset to continue.
`pageInfo`	No	Human-readable page position, e.g. "offset 0, showing 100 of 234". Use to construct the next offset.
`dimension`	No	The requested dimension type code.
`nextOffset`	No	Offset to request for the next page. Absent when this page reached the end of the values.
`totalCount`	No	Total values for this dimension and filter, before the limit is applied.

Schema Changelog

Changes observed during successful MCP inspections.

Changed6 schema fields changedAug 25, 2026

changedInput schema / $schema

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

addedInput schema / additionalProperties
```
Added value: +false
```

changedOutput schema / $schema

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

addedOutput schema / anyOf

Added value: +[
+  {
+    "not": {
+      "required": [
+        "error"
+      ]
+    },
+    "required": [
+      "dimension",
+      "values",
+      "totalCount",
+      "offset",
+      "hasMore",
+      "pageInfo"
+    ]
+  },
+  {
+    "required": [
+      "error"
+    ]
+  }
+]

addedOutput schema / properties / error

Added value: +{
+  "additionalProperties": {},
+  "description": "Present when the call failed. Absent on success.",
+  "properties": {
+    "code": {
+      "description": "JSON-RPC error code for this failure.",
+      "maximum": 9007199254740991,
+      "minimum": -9007199254740991,
+      "type": "integer"
+    },
+    "data": {
+      "additionalProperties": {},
+      "properties": {
+        "reason": {
+          "description": "Machine-readable failure mode. Declared by this tool: `dimension_not_found`: An unfiltered lookup of the dimension code returned no values at all — it does not exist in the GHO catalog. `malformed_identifier`: dimension carries an unpaired UTF-16 surrogate, so it cannot be encoded into the request URL. Other values are possible when a failure originates below the handler.",
+          "examples": [
+            "dimension_not_found",
+            "malformed_identifier"
+          ],
+          "type": "string"
+        },
+        "recovery": {
+          "additionalProperties": {},
+          "description": "Actionable next step for the caller.",
+          "properties": {
+            "hint": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "hint"
+          ],
+          "type": "object"
+        },
+        "retryable": {
+          "description": "Whether retrying may succeed.",
+          "type": "boolean"
+        }
+      },
+      "type": "object"
+    },
+    "message": {
+      "description": "Human-readable description of what went wrong.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "code",
+    "message"
+  ],
+  "type": "object"
+}

removedOutput schema / required

Removed value: -[
-  "dimension",
-  "values",
-  "totalCount",
-  "offset",
-  "hasMore",
-  "pageInfo"
-]

Changed11 schema fields changedAug 18, 2026

addedInput schema / properties / limit

Added value: +{
+  "default": 100,
+  "description": "Number of values to return per page. Default 100, max 500.",
+  "maximum": 500,
+  "minimum": 1,
+  "type": "integer"
+}

addedInput schema / properties / offset

Added value: +{
+  "default": 0,
+  "description": "Zero-based offset into the values for this dimension and filter. Default 0. Read hasMore and nextOffset from the response to continue paging. An offset at or beyond totalCount returns an empty values array, not an error.",
+  "maximum": 9007199254740991,
+  "minimum": 0,
+  "type": "integer"
+}

addedInput schema / properties / parent_code

Added value: +{
+  "description": "Restrict results to values under one parent, e.g. dimension=\"COUNTRY\" with parent_code=\"EUR\" for the countries in the WHO European Region. Only hierarchical dimensions carry a parent; a filter that matches nothing returns an empty page, not an error.",
+  "minLength": 1,
+  "type": "string"
+}

addedOutput schema / properties / hasMore

Added value: +{
+  "description": "True when more values remain beyond this page. Pair with nextOffset to continue.",
+  "type": "boolean"
+}

addedOutput schema / properties / nextOffset

Added value: +{
+  "description": "Offset to request for the next page. Absent when this page reached the end of the values.",
+  "type": "number"
+}

addedOutput schema / properties / notice

Added value: +{
+  "description": "Present when values were withheld, the parent_code filter matched nothing, or the requested offset ran past the end. Explains what to do next.",
+  "type": "string"
+}

addedOutput schema / properties / offset

Added value: +{
+  "description": "Zero-based offset this page started at.",
+  "type": "number"
+}

addedOutput schema / properties / pageInfo

Added value: +{
+  "description": "Human-readable page position, e.g. \"offset 0, showing 100 of 234\". Use to construct the next offset.",
+  "type": "string"
+}

addedOutput schema / properties / totalCount

Added value: +{
+  "description": "Total values for this dimension and filter, before the limit is applied.",
+  "type": "number"
+}

changedOutput schema / properties / values / description

Previous value: -"Valid values for this dimension type."New value: +"Valid values for this dimension type, for the requested page."

changedOutput schema / required

Previous value: -[
-  "dimension",
-  "values"
-]New value: +[
+  "dimension",
+  "values",
+  "totalCount",
+  "offset",
+  "hasMore",
+  "pageInfo"
+]

First observedMay 25, 2026

TDQS

A4.7/5.0

Behavior5/5

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

The annotations already declare readOnlyHint=true and idempotentHint=true, so the description adds valuable behavior beyond them: it notes paging is deterministic, explains that hierarchical dimensions use parent_code, and clarifies that offsets beyond totalCount return an empty array rather than an error. This gives the agent confidence in edge-case behavior.

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 two sentences, front-loading the core purpose and target dimensions, then immediately providing paging guidance. Every sentence earns its place with no fluff or repetition.

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?

Given the tool's moderate complexity (4 params, one optional filter), the description covers discovery, paging, and edge cases (empty arrays). Since an output schema exists, the description is not required to explain return values, and it doesn't need to—the offset parameter in the schema already mentions hasMore and nextOffset. All essential guidance is present.

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

Parameters4/5

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

Schema coverage is 100% with each parameter described, so the baseline is 3. The description enriches this by giving a concrete example of using dimension='COUNTRY' with parent_code='EUR', which clarifies how parent_code works for hierarchical dimensions. This adds meaning beyond the schema's individual descriptions.

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 names a specific verb ('List') and a specific resource ('valid codes and labels for a WHO GHO dimension type'), and explicitly lists example dimension types (COUNTRY, REGION, etc.). It distinguishes itself from siblings by stating it is used to discover filter values before calling who_query_indicator_data and to confirm ISO codes, which differentiates it from who_list_dimensions (which lists dimension type codes).

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?

It clearly states when to use the tool: 'Use this to discover valid filter values before calling who_query_indicator_data, or to confirm the correct ISO code for a country.' It also refers the user to who_list_dimensions for discovering dimension type codes, providing an alternative. It does not explicitly state when not to use it, but the guidance is clear and contextual.

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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