Open-Meteo MCP Server

Marine Weather

marine_weather

Read-onlyIdempotent

Retrieve marine weather forecasts including wave height, period, direction, and sea surface temperature for given coordinates.

Instructions

Get marine weather forecast including wave height, wave period, wave direction and sea surface temperature.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`daily`	No
`hourly`	No
`models`	No	Omit to use the default model.
`current`	No	Variables to return for the current time.
`end_date`	No	Date in YYYY-MM-DD format.
`latitude`	Yes
`timezone`	No	IANA time zone (e.g. "Europe/Paris"), or "auto" for the location's own. Default GMT.
`longitude`	Yes
`past_days`	No	Days before today to include, in addition to the forecast.
`start_date`	No	Date in YYYY-MM-DD format.
`timeformat`	No		iso8601
`length_unit`	No
`minutely_15`	No	Variables to return at 15-minute resolution.
`forecast_days`	No	Days to forecast, starting today.
`cell_selection`	No	Grid cell to use near a coastline: prefer "land", prefer "sea", or the "nearest" cell.
`wind_speed_unit`	No		kmh
`temperature_unit`	No		celsius

Schema Changelog

Changes observed during successful MCP inspections.

Changed25 schema fields changedv2.5.0Sep 28, 2026

addedInput schema / $schema

Added value: +"http://json-schema.org/draft-07/schema#"

addedInput schema / additionalProperties
```
Added value: +false
```

addedInput schema / properties / cell_selection

Added value: +{
+  "description": "Grid cell to use near a coastline: prefer \"land\", prefer \"sea\", or the \"nearest\" cell.",
+  "enum": [
+    "land",
+    "sea",
+    "nearest"
+  ],
+  "type": "string"
+}

addedInput schema / properties / current

Added value: +{
+  "description": "Variables to return for the current time.",
+  "items": {
+    "enum": [
+      "wave_height",
+      "wave_direction",
+      "wave_period",
+      "wave_peak_period",
+      "wind_wave_height",
+      "wind_wave_direction",
+      "wind_wave_period",
+      "wind_wave_peak_period",
+      "swell_wave_height",
+      "swell_wave_direction",
+      "swell_wave_period",
+      "swell_wave_peak_period",
+      "secondary_swell_wave_height",
+      "secondary_swell_wave_period",
+      "secondary_swell_wave_direction",
+      "tertiary_swell_wave_height",
+      "tertiary_swell_wave_period",
+      "tertiary_swell_wave_direction",
+      "sea_level_height_msl",
+      "sea_surface_temperature",
+      "ocean_current_velocity",
+      "ocean_current_direction",
+      "invert_barometer_height"
+    ],
+    "type": "string"
+  },
+  "type": "array"
+}

removedInput schema / properties / daily / description

Removed value: -"Daily marine weather variables to retrieve"

changedInput schema / properties / daily / items / enum

Previous value: -[
-  "wave_height_max",
-  "wind_wave_height_max",
-  "swell_wave_height_max"
-]New value: +[
+  "wave_height_max",
+  "wave_direction_dominant",
+  "wave_period_max",
+  "wind_wave_height_max",
+  "wind_wave_direction_dominant",
+  "wind_wave_period_max",
+  "wind_wave_peak_period_max",
+  "swell_wave_height_max",
+  "swell_wave_direction_dominant",
+  "swell_wave_period_max",
+  "swell_wave_peak_period_max"
+]

addedInput schema / properties / end_date

Added value: +{
+  "description": "Date in YYYY-MM-DD format.",
+  "pattern": "^\\d{4}-\\d{2}-\\d{2}$",
+  "type": "string"
+}

removedInput schema / properties / forecast_days / default
```
Removed value: -7
```

changedInput schema / properties / forecast_days / description

Previous value: -"Number of forecast days"New value: +"Days to forecast, starting today."

changedInput schema / properties / forecast_days / minimum
```
Previous value: -1New value: +0
```

removedInput schema / properties / hourly / description

Removed value: -"Marine weather variables to retrieve"

changedInput schema / properties / hourly / items / enum

Previous value: -[
-  "wave_height",
-  "wave_direction",
-  "wave_period",
-  "wind_wave_height",
-  "wind_wave_direction",
-  "wind_wave_period",
-  "swell_wave_height",
-  "swell_wave_direction",
-  "swell_wave_period",
-  "sea_surface_temperature"
-]New value: +[
+  "wave_height",
+  "wave_direction",
+  "wave_period",
+  "wave_peak_period",
+  "wind_wave_height",
+  "wind_wave_direction",
+  "wind_wave_period",
+  "wind_wave_peak_period",
+  "swell_wave_height",
+  "swell_wave_direction",
+  "swell_wave_period",
+  "swell_wave_peak_period",
+  "secondary_swell_wave_height",
+  "secondary_swell_wave_period",
+  "secondary_swell_wave_direction",
+  "tertiary_swell_wave_height",
+  "tertiary_swell_wave_period",
+  "tertiary_swell_wave_direction",
+  "sea_level_height_msl",
+  "sea_surface_temperature",
+  "ocean_current_velocity",
+  "ocean_current_direction",
+  "invert_barometer_height"
+]

removedInput schema / properties / latitude / description
```
Removed value: -"Latitude in WGS84 coordinate system"
```

addedInput schema / properties / length_unit

Added value: +{
+  "enum": [
+    "metric",
+    "imperial"
+  ],
+  "type": "string"
+}

removedInput schema / properties / longitude / description
```
Removed value: -"Longitude in WGS84 coordinate system"
```

addedInput schema / properties / minutely_15

Added value: +{
+  "description": "Variables to return at 15-minute resolution.",
+  "items": {
+    "enum": [
+      "ocean_current_velocity",
+      "ocean_current_direction",
+      "sea_level_height_msl"
+    ],
+    "type": "string"
+  },
+  "type": "array"
+}

addedInput schema / properties / models

Added value: +{
+  "description": "Omit to use the default model.",
+  "enum": [
+    "best_match",
+    "meteofrance_wave",
+    "meteofrance_currents",
+    "dwd_ewam",
+    "dwd_gwam",
+    "ewam",
+    "gwam",
+    "ecmwf_wam",
+    "ecmwf_wam025",
+    "ecmwf_wam025_ensemble",
+    "ecmwf_wam025_ensemble_mean",
+    "ncep_gfswave025",
+    "ncep_gefswave025",
+    "ncep_gefswave025_ensemble_mean",
+    "era5_ocean"
+  ],
+  "type": "string"
+}

changedInput schema / properties / past_days / description

Previous value: -"Include past days data"New value: +"Days before today to include, in addition to the forecast."

changedInput schema / properties / past_days / maximum
```
Previous value: -7New value: +92
```
changedInput schema / properties / past_days / minimum
```
Previous value: -1New value: +0
```

addedInput schema / properties / start_date

Added value: +{
+  "description": "Date in YYYY-MM-DD format.",
+  "pattern": "^\\d{4}-\\d{2}-\\d{2}$",
+  "type": "string"
+}

addedInput schema / properties / temperature_unit

Added value: +{
+  "default": "celsius",
+  "enum": [
+    "celsius",
+    "fahrenheit"
+  ],
+  "type": "string"
+}

addedInput schema / properties / timeformat

Added value: +{
+  "default": "iso8601",
+  "enum": [
+    "iso8601",
+    "unixtime"
+  ],
+  "type": "string"
+}

changedInput schema / properties / timezone / description

Previous value: -"Timezone for timestamps"New value: +"IANA time zone (e.g. \"Europe/Paris\"), or \"auto\" for the location's own. Default GMT."

addedInput schema / properties / wind_speed_unit

Added value: +{
+  "default": "kmh",
+  "enum": [
+    "kmh",
+    "ms",
+    "mph",
+    "kn"
+  ],
+  "type": "string"
+}

First observedv1.1.3Jan 31, 2026

TDQS

C2.9/5.0

Behavior3/5

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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds only the variable list, not model selection behavior, forecast horizon limits, or upstream data source semantics that would matter for a multi-model tool.

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?

A single tight sentence with the output content front-loaded and no filler. It is efficient, though arguably too sparse for a tool with 17 parameters.

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

Completeness2/5

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

For a 17-parameter tool with 6 enums, no output schema, and only 53% schema coverage, the description is far too thin. It never mentions the model choice, date-window controls, timezone/units, or resolution options that an agent must decide on before calling.

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?

Schema description coverage is 53%, so half the 17 parameters are undocumented anywhere. The description names a few variables that map to the daily/hourly enums, but says nothing about models, date ranges, cell_selection near coastlines, units, or minutely_15, all of which materially affect results.

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 (Get) and resource (marine weather forecast) and enumerates the core outputs (wave height, period, direction, sea surface temperature). It does not distinguish itself from generic siblings like weather_forecast or gfs_forecast, so it falls short of a 5.

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 on when to pick this over weather_forecast, gfs_forecast, or the other model-specific forecast tools that also cover ocean/marine variables. The marine framing implies usage but nothing is stated explicitly.

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

Deploy Server

Marine Weather

Instructions

Input Schema

Schema Changelog

TDQS

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