WeatherMCP
Provides access to US National Weather Service (NWS) data, allowing retrieval of weather alerts by state and weather forecasts for specific coordinates.
Click on "Install Server".
Wait a few minutes for the server to deploy. Once ready, it will show a "Started" state.
In the chat, type
@followed by the MCP server name and your instructions, e.g., "@WeatherMCPget alerts for California"
That's it! The server will respond to your query, and you can continue using it as needed.
Here is a step-by-step guide with screenshots.
WeatherMCP
This project is an MCP server built as a hands-on exercise. It provides weather data and alerts from the US National Weather Service (NWS) via a simple API using the FastMCP framework.
Features
Weather Alerts: Get active weather alerts for any US state.
Forecast: Retrieve weather forecasts for a specific latitude and longitude.
Related MCP server: Weather MCP Server
Requirements
Python 3.8+
uv (for dependency management and running)
Installation
Install dependencies using uv:
uv pip install -r requirements.txtOr, if you use
pyproject.toml:uv pip install -r pyproject.toml(Optional) Create a virtual environment:
uv venv .venv source .venv/bin/activate
Running the MCP Server
To start the server using uv:
uv pip install -e . # if you want to install as editable, or just ensure dependencies are installed
uv python weather.pyThe server will start and listen for MCP requests via stdio.
Available Tools
1. get_alerts(state: str)
Description: Get active weather alerts for a US state.
Argument:
state— Two-letter US state code (e.g.,CA,NY).Returns: Formatted string of current alerts or a message if none are found.
2. get_forecast(latitude: float, longitude: float)
Description: Get weather forecast for a specific location.
Arguments:
latitude— Latitude of the location (float)longitude— Longitude of the location (float)
Returns: Formatted string with the next 5 forecast periods.
Notes
This project is for educational and hands-on purposes.
Data is sourced from the National Weather Service API.
Feel free to extend or modify the project for your own experiments!
Available Tools
2 toolsget_alertsA
Get weather alerts for a US state.
Args:
state: Two-letter US state code (e.g. CA, NY)
| Name | Required | Description | Default |
|---|---|---|---|
| state | Yes |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, and the description does not disclose behavioral traits such as data source freshness, authentication requirements, rate limits, or error handling for invalid states. The agent is left uninformed about important runtime behaviors.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is extremely concise (two lines) with the purpose front-loaded. Every sentence adds value: the first states the action, the second clarifies the parameter. No wasted words.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a simple one-parameter tool with no output schema, the description is largely complete. It explains what the tool does and how to specify the input. However, it does not mention what the return value contains (e.g., alert details, count), which could be useful for an agent.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
With 0% schema description coverage, the description adds crucial meaning by specifying the parameter format ('Two-letter US state code') and providing examples (CA, NY). This adequately compensates for the missing schema descriptions.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the action ('Get') and resource ('weather alerts') with a specific scope ('for a US state'). It is unambiguous and distinguishes the tool's function even without sibling tools present.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description implies when to use the tool (when needing weather alerts for a US state) but does not provide explicit exclusions or alternatives. Since there are no sibling tools, this is acceptable but could be more prescriptive about valid state codes.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
get_forecastB
Get weather forecast for a location.
Args:
latitude: Latitude of the location
longitude: Longitude of the location
| Name | Required | Description | Default |
|---|---|---|---|
| latitude | Yes | ||
| longitude | Yes |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries full burden for behavioral disclosure. It states what the tool does but doesn't describe any behavioral traits - no information about rate limits, authentication needs, whether this is a read-only operation, what format the forecast returns, or any side effects. This is inadequate for a tool with zero annotation coverage.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is appropriately sized with a clear purpose statement followed by parameter documentation. The two-sentence structure is efficient, though the parameter documentation could be integrated more seamlessly rather than as a separate 'Args:' section. Every sentence serves a purpose.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given no annotations, no output schema, and a simple 2-parameter tool, the description is incomplete. It doesn't explain what the forecast returns (format, time range, metrics), any limitations (e.g., historical vs. future forecasts), or behavioral constraints. For a weather API tool, users need to know what data they'll receive.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
With 0% schema description coverage and 2 parameters, the description compensates well by explicitly listing both parameters ('latitude' and 'longitude') and providing basic semantic context ('Latitude of the location', 'Longitude of the location'). This adds meaningful information beyond the bare schema, though it doesn't specify format constraints or valid ranges.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the tool's purpose with 'Get weather forecast for a location' - a specific verb ('Get') and resource ('weather forecast') with scope ('for a location'). However, it doesn't differentiate from sibling tools like 'get_alerts' which might also relate to weather, so it doesn't reach the highest score.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description provides no guidance on when to use this tool versus alternatives. There's no mention of when-not scenarios, prerequisites, or comparison with sibling tools like 'get_alerts' (which might provide weather alerts instead of forecasts). The agent must infer usage from the name alone.
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.
2 tool updates
- First observed
get_alerts - First observed
get_forecast
TDQS
Scored across 2 tools
The two tools have clearly distinct purposes: get_alerts retrieves weather alerts for US states, while get_forecast provides forecasts for geographic coordinates. There is no overlap in functionality or ambiguity between them.
Both tools follow a consistent verb_noun naming pattern (get_alerts, get_forecast) with identical verb usage and snake_case formatting. The naming is perfectly predictable and uniform.
With only 2 tools, this server feels thin for a weather domain. It lacks basic operations like current conditions, historical data, or broader geographic coverage, making it insufficient for comprehensive weather-related tasks.
The tool surface is severely incomplete for weather functionality. It misses core operations such as current weather, historical data, multi-day forecasts, or international coverage, leaving significant gaps that will limit agent effectiveness.
Maintenance
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