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Kohei-Suzuki22

Weather MCP Server

by Kohei-Suzuki22
OverviewSchemaSourceRelated ServersDiscussionsAdmin
Python
Remote

Weather MCP Server

Model Context Protocol (MCP) サーバーの実装プロジェクトです。天気情報を提供するツールを実装します。

参考ドキュメント

Related MCP server: Weather MCP Server

システム要件

  • Python 3.10以上

  • uv (Pythonパッケージマネージャー)

セットアップ

# 仮想環境の作成とアクティベート
uv venv
source .venv/bin/activate

# 依存関係のインストール
uv add "mcp[cli]" httpx

実行方法

uv run main.py

提供するツール

ツール名

説明

get_alerts

米国の州の気象警報を取得

get_forecast

緯度・経度から天気予報を取得

Claude for Desktop への統合

~/Library/Application Support/Claude/claude_desktop_config.json を編集：

{
  "mcpServers": {
    "weather": {
      "command": "uv",
      "args": [
        "--directory",
        "/ABSOLUTE/PATH/TO/weather",
        "run",
        "main.py"
      ]
    }
  }
}

処理の流れ (What's happening under the hood)

Claude for Desktopでの質問から回答までの流れ：

┌─────────────────┐     ┌─────────────────┐     ┌─────────────────┐
│  Claude Desktop │     │   MCP Server    │     │  External API   │
│    (Client)     │     │   (weather)     │     │  (weather.gov)  │
└────────┬────────┘     └────────┬────────┘     └────────┬────────┘
         │                       │                       │
         │  1. ユーザーが質問     │                       │
         │  「サクラメントの天気は？」                      │
         │                       │                       │
         │  2. Claudeが利用可能な │                       │
         │     ツールを分析       │                       │
         │                       │                       │
         │  3. ツール実行リクエスト│                       │
         │  (JSON-RPC over STDIO)│                       │
         │──────────────────────>│                       │
         │                       │  4. 外部API呼び出し    │
         │                       │──────────────────────>│
         │                       │                       │
         │                       │  5. APIレスポンス      │
         │                       │<──────────────────────│
         │  6. ツール実行結果     │                       │
         │<──────────────────────│                       │
         │                       │                       │
         │  7. Claudeが結果を解釈 │                       │
         │     して自然言語で回答 │                       │
         │                       │                       │

ポイント

  • 自動起動: Claude Desktopが設定に基づいてMCPサーバープロセスを起動・管理

  • ツール検出: クライアントがサーバーの tools/list を呼び出して利用可能なツールを取得

  • STDIO通信: 標準入出力を介してJSON-RPCメッセージをやり取り

  • 非同期実行: API呼び出しなどのI/O操作を効率的に処理

注意事項

  • STDIOベースのサーバーでは print() を使用しないこと（JSON-RPCメッセージが破損する）

  • ログ出力には logging モジュールを使用する

Available Tools

2 tools
get_alertsA

Get weather alerts for a US state.

Args: state: Two-letter US state code (e.g. CA, NY)

ParametersJSON Schema
NameRequiredDescriptionDefault
stateYes

Output Schema

ParametersJSON Schema
NameRequiredDescription
resultYes

TDQS

A4.4/5.0
Behavior3/5

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

No annotations are provided, so the description carries the full behavioral burden. 'Get' implies a read-only operation, but the description does not explicitly state side-effect-free behavior or any caveats about alert types or data source. It is not misleading, but it adds minimal behavioral context beyond what the name implies.

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 extremely concise, with a front-loaded purpose statement followed by a compact Args block. Every sentence earns its place and there is no filler.

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?

With a single well-documented parameter, an output schema, and no siblings, the description plus schema fully covers what an agent needs to invoke the tool correctly. No missing context for this simple operation.

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?

Schema description coverage is 0%, yet the description fully compensates by specifying the parameter format ('Two-letter US state code') and providing concrete examples ('CA, NY'). This adds real meaning beyond the raw schema type string.

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 states a specific verb ('Get'), a clear resource ('weather alerts'), and a clear scope ('US state'). It is unambiguous and leaves no doubt about what the tool does, even without siblings to differentiate from.

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?

There are no sibling tools, so explicit routing guidance is unnecessary. The description clearly implies usage: when you need weather alerts for a US state. It lacks explicit exclusions, but nothing is misleading or missing for a tool of this simplicity.

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

get_forecastC

Get weather forecast for a location.

Args: latitude: Latitude of the location longitude: Longitude of the location

ParametersJSON Schema
NameRequiredDescriptionDefault
latitudeYes
longitudeYes

Output Schema

ParametersJSON Schema
NameRequiredDescription
resultYes

TDQS

C2.8/5.0
Behavior2/5

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

There are no annotations, so the description must carry behavioral context. It only says 'get' a forecast and gives no indication of units, time range, coordinate format, or whether this is a read-only operation. Nothing contradicts annotations, but little is disclosed beyond the basic action.

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 short and the core purpose is front-loaded. The Args block is somewhat redundant with the schema but does not add significant bloat, keeping the overall entry compact.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The description provides the essential call requirements (latitude and longitude) and the presence of an output schema reduces the need to document return values. However, it omits practical context like expected coordinate units, available forecast periods, and why an agent would choose this over get_alerts.

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

Parameters2/5

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

The Args section repeats the parameter names with minimal glosses ('Latitude of the location'), adding almost no meaning beyond the schema titles. Since schema description coverage is 0%, the description should compensate with coordinate format or range details, but it does not.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description uses a clear verb and resource: 'Get weather forecast for a location'. It does not explicitly mention the sibling get_alerts, but the forecast-vs-alerts distinction is clear enough from the domain.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines2/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

No guidance is given about when to use this tool instead of get_alerts, nor are any exclusions or alternative conditions provided. The intended usage is only implied by the tool name and description.

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

Tool Schema Changelog

Recent tool additions, removals, and schema changes observed during successful MCP inspections.

  1. 2 tool updatesv1.0.0
    • First observedget_alerts
    • First observedget_forecast
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TDQS

B3.1/5.0

Scored across 2 tools

Disambiguation5/5

The two tools have clearly distinct purposes: get_alerts retrieves alerts for US states, while get_forecast provides forecasts for geographic coordinates. There is no overlap in functionality or ambiguity between them.

Naming Consistency5/5

Both tools follow a consistent verb_noun pattern (get_alerts, get_forecast) with the same verb style and snake_case convention. The naming is perfectly uniform and predictable.

Tool Count2/5

With only 2 tools, the server feels thin for a weather domain. It lacks basic operations like current conditions, historical data, or location search, making it borderline too minimal for practical use.

Completeness2/5

The tool surface is severely incomplete for a weather server. It misses core functionalities such as current weather, location lookup, radar data, and unit conversion, leaving significant gaps that will hinder agent workflows.

Resources

Related MCP Connectors

Related MCP Servers

  • Weather MCP Server

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    A
    license
    B
    quality
    D
    maintenance
    Provides tools to fetch real-time weather data from the National Weather Service API, allowing users to retrieve weather alerts by state and detailed forecasts by coordinates.
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  • Weather MCP Server

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    Provides weather information and alerts from the National Weather Service, including active weather alerts for US states and location-based forecasts using latitude/longitude coordinates.
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  • MCP Weather Server

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    quality
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