Japan Agent API

Japan weather warnings by prefecture (JMA)

jp_warnings

Read-only

Which JMA weather emergency warnings, warnings and advisories are in effect in this Japanese prefecture now? Structured JSON in English and Japanese (type, level, status, areas with JMA's English names, issued_at, source URL). Relay only; no independent forecast.

Input Schema

Name	Required	Description	Default
`prefecture`	Yes	Japanese prefecture: English name (e.g. "Tokyo", "Osaka", "Hokkaido"; "Tokyo-to" and "Osaka Prefecture" also work), Japanese name in kanji, or JIS code "01".."47".
`include_municipalities`	No	Also list every municipality (Japanese and English names) per warning. Default false.

Output Schema

Name	Required	Description
`terms`	Yes	URL of the terms of service.
`counts`	Yes
`region`	Yes
`source`	Yes	Data source and processor.
`coverage`	Yes	complete = the current status of every forecast area was confirmed (JMA XML bulletin or JMA website current-status data); partial = some not confirmed; unknown = none confirmed (see missing_offices; not 'no warnings').
`warnings`	Yes	Warnings and advisories in effect (type, level, status, areas).
`bulletins`	Yes
`prefecture`	Yes
`provenance`	Yes	Freshness receipts for every upstream source used.
`license_note`	Yes
`responded_at`	Yes
`retrieved_at`	Yes	When the upstream data was retrieved (ISO 8601).
`danger_notice`	Yes
`forecast_areas`	Yes
`missing_offices`	Yes
`lifted_in_latest_bulletin`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedOct 11, 2026

changedOutput schema / properties / coverage / description

Previous value: -"complete = every forecast area has a usable latest bulletin; partial = some missing; unknown = none."New value: +"complete = the current status of every forecast area was confirmed (JMA XML bulletin or JMA website current-status data); partial = some not confirmed; unknown = none confirmed (see missing_offices; not 'no warnings')."

Changed1 schema field changedOct 11, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "additionalProperties": {},
+  "properties": {
+    "bulletins": {
+      "items": {
+        "additionalProperties": {},
+        "properties": {},
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "counts": {
+      "additionalProperties": {},
+      "properties": {
+        "advisory": {
+          "type": "number"
+        },
+        "emergency": {
+          "type": "number"
+        },
+        "warning": {
+          "type": "number"
+        }
+      },
+      "required": [
+        "emergency",
+        "warning",
+        "advisory"
+      ],
+      "type": "object"
+    },
+    "coverage": {
+      "description": "complete = every forecast area has a usable latest bulletin; partial = some missing; unknown = none.",
+      "enum": [
+        "complete",
+        "partial",
+        "unknown"
+      ],
+      "type": "string"
+    },
+    "danger_notice": {
+      "type": "boolean"
+    },
+    "forecast_areas": {
+      "items": {
+        "additionalProperties": {},
+        "properties": {
+          "code": {
+            "type": "string"
+          },
+          "en": {
+            "type": "string"
+          },
+          "ja": {
+            "type": "string"
+          }
+        },
+        "required": [
+          "code",
+          "en",
+          "ja"
+        ],
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "license_note": {
+      "type": "string"
+    },
+    "lifted_in_latest_bulletin": {
+      "items": {
+        "additionalProperties": {},
+        "properties": {},
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "missing_offices": {
+      "items": {
+        "additionalProperties": {},
+        "properties": {
+          "office_code": {
+            "type": "string"
+          },
+          "reason": {
+            "type": "string"
+          }
+        },
+        "required": [
+          "office_code",
+          "reason"
+        ],
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "prefecture": {
+      "additionalProperties": {},
+      "properties": {
+        "en": {
+          "type": "string"
+        },
+        "ja": {
+          "type": "string"
+        },
+        "jis": {
+          "type": "string"
+        }
+      },
+      "required": [
+        "jis",
+        "en",
+        "ja"
+      ],
+      "type": "object"
+    },
+    "provenance": {
+      "description": "Freshness receipts for every upstream source used.",
+      "items": {
+        "additionalProperties": {},
+        "description": "Freshness receipt for one upstream source.",
+        "properties": {
+          "content_sha256": {
+            "type": [
+              "string",
+              "null"
+            ]
+          },
+          "fetch_status": {
+            "description": "found / empty / stale / unavailable / unsupported (see catalog fetch_status_values).",
+            "enum": [
+              "found",
+              "empty",
+              "stale",
+              "unavailable",
+              "unsupported"
+            ],
+            "type": "string"
+          },
+          "parser_version": {
+            "type": "string"
+          },
+          "processed_by": {
+            "type": "string"
+          },
+          "retrieved_at": {
+            "description": "When this service retrieved the upstream data (null if unknown).",
+            "type": [
+              "string",
+              "null"
+            ]
+          },
+          "source": {
+            "additionalProperties": {},
+            "description": "Publisher and URL of the upstream document or dataset.",
+            "properties": {
+              "publisher": {
+                "type": "string"
+              },
+              "url": {
+                "type": "string"
+              }
+            },
+            "required": [
+              "publisher",
+              "url"
+            ],
+            "type": "object"
+          },
+          "upstream_updated_at": {
+            "description": "Update time stated by the upstream, or null when it states none.",
+            "type": [
+              "string",
+              "null"
+            ]
+          }
+        },
+        "required": [
+          "source",
+          "upstream_updated_at",
+          "retrieved_at",
+          "content_sha256",
+          "parser_version",
+          "fetch_status",
+          "processed_by"
+        ],
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "region": {
+      "anyOf": [
+        {
+          "additionalProperties": {},
+          "properties": {
+            "code": {
+              "type": "string"
+            },
+            "en": {
+              "type": "string"
+            },
+            "ja": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "code",
+            "en",
+            "ja"
+          ],
+          "type": "object"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    },
+    "responded_at": {
+      "type": "string"
+    },
+    "retrieved_at": {
+      "description": "When the upstream data was retrieved (ISO 8601).",
+      "type": "string"
+    },
+    "source": {
+      "description": "Data source and processor.",
+      "type": "string"
+    },
+    "terms": {
+      "description": "URL of the terms of service.",
+      "type": "string"
+    },
+    "warnings": {
+      "description": "Warnings and advisories in effect (type, level, status, areas).",
+      "items": {
+        "additionalProperties": {},
+        "properties": {
+          "issued_at": {
+            "type": "string"
+          },
+          "office_code": {
+            "type": "string"
+          },
+          "source_url": {
+            "type": "string"
+          }
+        },
+        "required": [
+          "office_code",
+          "issued_at",
+          "source_url"
+        ],
+        "type": "object"
+      },
+      "type": "array"
+    }
+  },
+  "required": [
+    "prefecture",
+    "region",
+    "forecast_areas",
+    "coverage",
+    "missing_offices",
+    "counts",
+    "danger_notice",
+    "warnings",
+    "lifted_in_latest_bulletin",
+    "bulletins",
+    "provenance",
+    "source",
+    "retrieved_at",
+    "responded_at",
+    "license_note",
+    "terms"
+  ],
+  "type": "object"
+}

First observedOct 11, 2026

TDQS

A3.9/5.0

Behavior4/5

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

Annotations already cover readOnlyHint and openWorldHint, so the bar is lower. The description adds real value beyond them: it declares the tool is a pure relay of JMA data with no independent forecasting, that results are bilingual, and that it reflects conditions 'now' rather than history. It stops short of stating caching or freshness latency, which would have pushed it higher.

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?

Two sentences, no filler, with the core question front-loaded and the return shape summarized in a parenthetical. The rhetorical question opener is slightly indirect but still efficient; nothing is wasted.

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?

Given an output schema exists, the description need not explain return values, yet it usefully previews the field set and language coverage. Combined with annotations covering safety and open-world behavior, an agent has enough to call it correctly; only latency/freshness semantics for '(now)' are left unstated.

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 description coverage is 100%, so the schema already explains the prefecture formats and the include_municipalities flag. The description adds nothing beyond that for parameters (the mention of 'areas' refers to output, not input). Baseline 3 is appropriate when the schema does all the work.

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 and resource ('Which JMA weather emergency warnings, warnings and advisories are in effect'), scopes it to a Japanese prefecture and to the present moment, and enumerates the payload. An agent can immediately distinguish it from jp_typhoons or jp_volcanoes because the resource is prefecture-level weather warnings.

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 implied rather than stated: 'in effect ... now' tells the agent this is a current-conditions lookup for one prefecture, and 'Relay only; no independent forecast' constrains downstream use. However, it never says when to prefer this over jp_trip_impact_check or jp_typhoons, nor any prerequisites, so guidance is only implied.

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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