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Tools

6 tools for working with WHO Global Health Observatory data:

Tool	Description
who_search_indicators	Search the GHO indicator catalog by keyword in indicator names
who_list_indicators	Browse the full indicator catalog with pagination
who_get_indicator_metadata	Fetch indicator names and supported filter dimensions for up to 10 codes
who_list_dimensions	List all dimension type codes available in the GHO API
who_list_dimension_values	List valid codes and labels for a dimension type (COUNTRY, REGION, SEX, etc.)
who_query_indicator_data	Query data rows for an indicator with spatial, temporal, and dimension filters

who_search_indicators

Search the WHO GHO indicator catalog by keyword.

• Substring match on indicator names — try terms like "life expectancy", "immunization", "mortality", "diabetes", or "HIV"
• Returns indicator codes and display names for use with who_query_indicator_data
• Offset-based pagination (offset) over the filtered result set; reports totalCount, hasMore, pageInfo, nextOffset
• Default limit 20, max 100

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who_list_indicators

Browse the full indicator catalog with offset-based pagination.

• No keyword required — lists all 3,059+ indicators
• Pagination via limit (default 50, max 500) and offset
• Returns total and hasMore for iteration

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who_get_indicator_metadata

Fetch metadata for one to ten indicator codes in a single call.

• Returns the full indicator name and the dimension types it supports (e.g. COUNTRY, SEX, REGION, AGEGROUP)
• Call before who_query_indicator_data to confirm which filter dimensions are valid
• Roughly 1,300 catalog indicators have no dimension listing upstream — those return dimensions: [] plus a dimensionsNote pointing at dim1Type/dim2Type on a sample data row, not a not-found
• Codes absent from the catalog are reported in notFound rather than raising an error

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who_list_dimensions

List all dimension type codes available in the GHO API.

• Returns every dimension type with its human-readable title
• Common types: COUNTRY, REGION, SEX, WORLDBANKINCOMEGROUP, AGEGROUP
• Use to discover codes before calling who_list_dimension_values

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who_list_dimension_values

List valid filter values for a single dimension type.

• Returns codes and labels for the dimension's values (e.g. the 234 country entries, the 43 WHO region codes)
• Includes optional parent hierarchy fields (parentCode, parentLabel, parentDimension)
• parent_code narrows hierarchical dimensions — dimension: "COUNTRY", parent_code: "EUR" returns the 58 country entries in the WHO European Region
• Deterministic ordering by Code with offset-based pagination (offset); returns totalCount, hasMore, pageInfo, nextOffset
• Default limit 100, max 500 — GHO (3,103 values) and DHSMICSGEOREGION (4,932) need paging
• A parent_code that matches nothing returns an empty page, not an error; only an unfiltered empty result means the dimension does not exist
• Use to confirm exact codes before passing them to who_query_indicator_data

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who_query_indicator_data

Query data rows for a single WHO GHO indicator.

• Spatial filters (mutually exclusive): country_codes (ISO 3166-1 alpha-3), region_codes (WHO regions), or income_group_codes (World Bank groups)
• Time range filter: year_from / year_to
• Sex filter: SEX_BTSX (both), SEX_FMLE, SEX_MLE — only applies when the indicator uses SEX as its first cross-cutting dimension
• Arbitrary dim1_value for indicators using non-SEX cross-cutting dimensions
• Optional uncertainty interval bounds (low/high) via include_uncertainty (default true)
• Deterministic row ordering (sort: year_desc default or year_asc) with offset-based pagination (offset); returns totalRows, hasMore, pageInfo, nextOffset
• Default limit 200, max 1000
• Primary data tool in the find-then-query workflow

Resources

Type	URI	Description
Resource	who://indicator/{indicatorCode}/metadata	Indicator name and supported filter dimensions for a single code
Resource	who://dimension/{dimensionCode}/values	First 100 values for a dimension type
Resource	who://dimension/{dimensionCode}/values{?limit,offset}	One explicit page of a dimension type's values
Resource	who://dimension/{dimensionCode}/values{?limit,offset,parentCode}	One explicit page, narrowed to a parent code

The three dimension-value URIs are registered separately because the MCP SDK's RFC 6570 matcher treats every query variable as required — a single template with optional variables would stop matching the bare URI. Supply every variable a template names.

Recommended workflow

1. who_search_indicators — find indicator codes by keyword
2. who_get_indicator_metadata — confirm which filter dimensions the indicator supports
3. who_query_indicator_data — fetch data with country/region/year/sex filters

To look up filter codes: who_list_dimensions → who_list_dimension_values.

Features

Built on @cyanheads/mcp-ts-core:

• Declarative tool definitions — single file per tool, framework handles registration and validation
• Unified error handling across all tools
• Pluggable auth (none, jwt, oauth)
• Swappable storage backends: in-memory, filesystem, Supabase, Cloudflare KV/R2/D1
• Structured logging with optional OpenTelemetry tracing
• Runs locally (stdio/HTTP) or on Cloudflare Workers from the same codebase

WHO GHO-specific:

• Full coverage of the WHO GHO OData API v2 — indicators, dimensions, dimension values, and data queries
• Configurable base URL and request timeout for custom or mirrored deployments
• Parallel metadata fan-out for multi-code indicator lookups

Agent-friendly output:

• Tool descriptions encode the cross-tool workflow — agents discover the right call order from descriptions alone
• Structured truncation signaling (truncated, truncatedNote, hasMore) so agents can decide whether to paginate
• Discriminated error codes with recovery hints on every failure path

Getting started

Self-Hosted / Local

Add the following to your MCP client configuration file.

{
  "mcpServers": {
    "who-gho-mcp-server": {
      "type": "stdio",
      "command": "bunx",
      "args": ["@cyanheads/who-gho-mcp-server@latest"],
      "env": {
        "MCP_TRANSPORT_TYPE": "stdio",
        "MCP_LOG_LEVEL": "info"
      }
    }
  }
}

Or with npx (no Bun required):

{
  "mcpServers": {
    "who-gho-mcp-server": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "@cyanheads/who-gho-mcp-server@latest"],
      "env": {
        "MCP_TRANSPORT_TYPE": "stdio",
        "MCP_LOG_LEVEL": "info"
      }
    }
  }
}

Or with Docker:

{
  "mcpServers": {
    "who-gho-mcp-server": {
      "type": "stdio",
      "command": "docker",
      "args": ["run", "-i", "--rm", "-e", "MCP_TRANSPORT_TYPE=stdio", "ghcr.io/cyanheads/who-gho-mcp-server:latest"]
    }
  }
}

For Streamable HTTP, set the transport and start the server:

MCP_TRANSPORT_TYPE=http MCP_HTTP_PORT=3010 bun run start:http
# Server listens at http://localhost:3010/mcp

Prerequisites

• Bun v1.3.0 or higher (or Node.js ≥24).
• No API key required — the WHO GHO API is public.

Installation

1. Clone the repository:

git clone https://github.com/cyanheads/who-gho-mcp-server.git

2. Navigate into the directory:

cd who-gho-mcp-server

3. Install dependencies:

bun install

Configuration

All configuration is validated at startup via Zod schemas in src/config/server-config.ts. Key environment variables:

Variable	Description	Default
MCP_TRANSPORT_TYPE	Transport: stdio or http	stdio
MCP_HTTP_PORT	HTTP server port	3010
MCP_HTTP_ENDPOINT_PATH	HTTP endpoint path where the MCP server is mounted	/mcp
MCP_PUBLIC_URL	Public origin override for TLS-terminating reverse-proxy deployments	none
MCP_AUTH_MODE	Authentication: none, jwt, or oauth	none
MCP_LOG_LEVEL	Log level (debug, info, warning, error, etc.)	info
MCP_GC_PRESSURE_INTERVAL_MS	Opt-in Bun-only forced-GC pressure loop (ms). Try 60000 if RSS grows under sustained HTTP load.	0 (disabled)
LOGS_DIR	Directory for log files (Node.js only)	<project-root>/logs
STORAGE_PROVIDER_TYPE	Storage backend: in-memory, filesystem, supabase, cloudflare-kv/r2/d1	in-memory
GHO_BASE_URL	WHO GHO OData API base URL (override for custom/mirrored deployments)	https://ghoapi.azureedge.net/api/
GHO_REQUEST_TIMEOUT_MS	HTTP request timeout in milliseconds	30000
OTEL_ENABLED	Enable OpenTelemetry	false

Running the server

Local development

• Build and run the production version:

  # One-time build
  bun run rebuild
  
  # Run the built server
  bun run start:http
  # or
  bun run start:stdio
  

• Run checks and tests:

  bun run devcheck  # Lints, formats, type-checks, and more
  bun run test      # Runs the test suite
  

Project structure

Directory	Purpose
src/mcp-server/tools	Tool definitions (*.tool.ts). Six tools across indicator discovery, dimension lookup, and data queries.
src/mcp-server/resources	Resource definitions. Indicator metadata and dimension values resources.
src/services/gho	WHO GHO OData API service layer — HTTP client, query builder, types.
src/config	Server-specific environment variable parsing and validation with Zod.
tests/	Unit and integration tests, mirroring the src/ structure.

Development guide

See CLAUDE.md for development guidelines and architectural rules. The short version:

• Handlers throw, framework catches — no try/catch in tool logic
• Use ctx.log for logging, ctx.state for storage
• Register new tools and resources in the createApp() arrays

Contributing

Issues and pull requests are welcome. Run checks and tests before submitting:

bun run devcheck
bun run test

License

This project is licensed under the Apache 2.0 License. See the LICENSE file for details.