JMA Data MCP

Get Weather By Location

get_weather_by_location

Read-onlyIdempotent

Retrieves current weather from the nearest AMeDAS station using latitude and longitude coordinates.

Instructions

Get current weather from the nearest AMeDAS station to given coordinates.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "lat": "<lat>",
      "lon": "<lon>"
    },
    "name": "get_weather_by_location"
  }
}

Input Schema

Name	Required	Description	Default
`lat`	Yes	Latitude in decimal degrees
`lon`	Yes	Longitude in decimal degrees

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

Changed3 schema fields changedv0.2.1May 1, 2026
- addedInput schema / additionalProperties
```
Added value: +false
```
- addedInput schema / properties / lat / description
```
Added value: +"Latitude in decimal degrees"
```
- addedInput schema / properties / lon / description
```
Added value: +"Longitude in decimal degrees"
```
First observedDec 19, 2025

TDQS

A3.6/5.0

Behavior3/5

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

Annotations already declare readOnly, idempotent, openWorld, and non-destructive, so the safety profile is covered. The description adds one genuinely useful behavioral fact — that observations come from the nearest station rather than the exact point — but says nothing about what happens when no station is nearby (ocean, remote areas) or how stale the reading may be.

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?

A single front-loaded sentence with no filler; the mechanism ('nearest AMeDAS station') is stated immediately after the verb. Nothing here is redundant.

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

Completeness4/5

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

An output schema exists, so return values need not be explained, and both parameters are schema-documented. The only real gap is the absence of edge-case behavior for coordinates with no nearby station, which matters for an open-world lookup.

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 coverage is 100% with both lat and lon documented in decimal degrees, so the schema does the heavy lifting and baseline 3 applies. The description confirms the coordinates drive nearest-station resolution but adds no format, range, or precision guidance beyond the schema.

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?

States a specific verb and resource ('Get current weather') plus the mechanism ('nearest AMeDAS station'), which separates it from get_current_weather and get_historical_weather. It does not name those siblings explicitly, so an agent must infer the routing, but the coordinate-based scope is unambiguous.

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

Usage Guidelines3/5

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

Usage is only implied: the required lat/lon parameters suggest 'use this when you have coordinates rather than a station ID.' There is no explicit statement of when to prefer it over get_current_weather or search_nearby_stations, nor any mention of prerequisites or coverage limits.

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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