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noaa-marine-mcp-server

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Get Tidal Currents

noaa_marine_get_currents
Read-onlyIdempotent

Tidal current predictions for a CO-OPS current station: max flood and ebb speeds, slack times, and the station's mean flood and ebb bearings. These are forecast predictions from CO-OPS, distinct from noaa_marine_get_current_profile, which returns NDBC observed ocean-current measurements binned by depth. The default MAX_SLACK interval is the practical planning view, showing when currents peak and when slack water occurs, and a 6-minute interval returns the continuous curve for detailed analysis, each row carrying its own flood/ebb/slack sense. A station can publish predictions for several depth bins at different depths: bin selects one, omitting it takes the CO-OPS default of the shallowest bin, and the bin and its depth are echoed on every response — read bins[] on a noaa_marine_find_stations current row for the bins a station actually has. A station whose currents CO-OPS will not predict as discrete events answers with an empty list and its own wording in the notice rather than an error. Both intervals are bounded by response size: a range whose rows fit is returned whole, a longer one returns the leading rows with rows_matched, rows_returned, and next_offset reporting how much matched and which offset reaches the rest, and offset and limit walk whichever series the interval selects. Current station IDs are alphanumeric (e.g. ACT4176), distinct from the numeric tide and water-level IDs, and the date range is limited to 1 year per request — use noaa_marine_find_stations with types=["current"] to obtain a valid current station ID.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
binNoDepth bin to predict for, taken from the bins[] array on a noaa_marine_find_stations current row (e.g. 15, 10 or 1 at PUG1515). Omit to take the CO-OPS default, which is the shallowest bin. A bin the station does not publish comes back as bin_unavailable naming the bins it does.
limitNoMaximum prediction rows to return on this page — max/slack events or 6-minute rows, whichever the interval selects — for a caller that wants fewer than the response budget allows. Omit for the largest page that fits; a value larger than the budget allows does not widen the page.
unitsNoUnit system: english = knots for speed and feet for the echoed depth; metric = cm/s for speed (not m/s) and meters for the echoed depth.english
offsetNoRow offset into the matched prediction series — the max/slack events on the MAX_SLACK interval, the 6-minute curve on 6min — for reading a range whose rows do not fit one response. 0 (default) starts at the first row; pass the next_offset from a previous call to continue. An offset past the last row returns an empty page rather than an error.
end_dateYesEnd date (inclusive), YYYYMMDD or YYYY-MM-DD, e.g. "20240607" or "2024-06-07".
intervalNoPrediction interval: MAX_SLACK (default) returns max flood, max ebb, and slack water events — ideal for passage planning. 6min returns a continuous current curve.MAX_SLACK
time_zoneNoTime zone for returned timestamps. lst_ldt = local standard/daylight time (default); gmt = UTC; lst = local standard time year-round.lst_ldt
begin_dateYesStart date, YYYYMMDD or YYYY-MM-DD, e.g. "20240601" or "2024-06-01".
station_idYesCO-OPS current station ID (alphanumeric, e.g. "ACT4176"). Obtain from noaa_marine_find_stations with types=["current"].

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
binNoDepth bin CO-OPS answered with — the requested bin, or its default shallowest bin when none was requested. Null when the response carried no prediction rows.
depthNoDepth of the returned bin, in the requested units: feet under english, meters under metric. Distinct from the bins[].depth on a noaa_marine_find_stations row, which the catalog always publishes in feet. Null when CO-OPS publishes no depth for the bin, or when the response carried no prediction rows.
errorNoPresent when the call failed. Absent on success.
unitsNoUnit system these values are in: "english" (speed in knots, depth in feet) or "metric" (speed in cm/s, depth in meters).
eventsNoMax flood, max ebb, and slack events — the whole matched series when it fits one response, otherwise the leading page starting at offset. Present for MAX_SLACK interval, and empty when CO-OPS answered with a statement instead of events — read notice for its wording.
noticeNoCO-OPS's own statement about the station when it returned that instead of prediction events — the answer to report, not a failure — or what this page of the prediction series covers and how to reach the next one.
truncatedNoTrue when this page stops short of the last matched row, so further rows remain at next_offset. False on the final page and on a page past the end. Absent when the whole matched series was returned.
station_idNoStation ID echoed from the request — for chaining.
next_offsetNoOffset to pass as offset on the next call, or null when this page reaches the last matched row. Absent when the whole matched series was returned.
page_offsetNoRow offset this page starts at, echoed from the request. Absent when the whole matched series was returned.
predictionsNo6-minute continuous current predictions — the whole curve when it fits one response, otherwise the leading page starting at offset. Present for 6min interval, and empty when CO-OPS answered with a statement instead of a curve — read notice for its wording.
rows_matchedNoPrediction rows the requested date range matched, before the page was cut. Absent when the whole matched series was returned.
station_nameNoStation name as returned by CO-OPS.
rows_returnedNoPrediction rows this page carries — the length of events on the MAX_SLACK interval, of predictions on 6min. Absent when the whole matched series was returned.

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed6 schema fields changed
    • changedInput schema / properties / begin_date / description
      Previous value: -"Start date in YYYYMMDD format, e.g. \"20240601\"."New value: +"Start date, YYYYMMDD or YYYY-MM-DD, e.g. \"20240601\" or \"2024-06-01\"."
    • changedInput schema / properties / begin_date / pattern
      Previous value: -"^\\d{8}$"New value: +"^(\\d{8}|\\d{4}-\\d{2}-\\d{2})$"
    • changedInput schema / properties / end_date / description
      Previous value: -"End date in YYYYMMDD format (inclusive), e.g. \"20240607\"."New value: +"End date (inclusive), YYYYMMDD or YYYY-MM-DD, e.g. \"20240607\" or \"2024-06-07\"."
    • changedInput schema / properties / end_date / pattern
      Previous value: -"^\\d{8}$"New value: +"^(\\d{8}|\\d{4}-\\d{2}-\\d{2})$"
    • changedOutput schema / properties / error / properties / data / properties / reason / description
      Previous value: -"Machine-readable failure mode. Declared by this tool: `station_not_found`: CO-OPS rejected the station ID as unknown or invalid — current stations require alphanumeric IDs. `invalid_date_range`: begin_date/end_date is not a real calendar date or begin_date is after end_date `date_range_exceeded`: Requested date range exceeds the 1-year CO-OPS limit. `no_predictions`: Station exists but CO-OPS returned no current-prediction data for the requested date range. `predictions_unavailable`: The station is in the current-predictions catalog, but CO-OPS publishes no current predictions for it at any date. `bin_unavailable`: CO-OPS rejected the requested bin because the station publishes no predictions at that bin. Other values are possible when a failure originates below the handler."New value: +"Machine-readable failure mode. Declared by this tool: `station_not_found`: CO-OPS rejected the station ID as unknown or invalid — current stations require alphanumeric IDs. `invalid_date_range`: begin_date/end_date is not a real calendar date or begin_date is after end_date. `date_range_exceeded`: Requested date range exceeds the 1-year CO-OPS limit. `no_predictions`: Station exists but CO-OPS returned no current-prediction data for the requested date range. `predictions_unavailable`: The station is in the current-predictions catalog, but CO-OPS publishes no current predictions for it at any date. `bin_unavailable`: CO-OPS rejected the requested bin because the station publishes no predictions at that bin. `upstream_throttled`: CO-OPS answered HTTP 403, which it returns for about two minutes while it throttles a burst of requests from one address. Other values are possible when a failure originates below the handler."
    • changedOutput schema / properties / error / properties / data / properties / reason / examples
      Previous value: -[
-  "station_not_found",
-  "invalid_date_range",
-  "date_range_exceeded",
-  "no_predictions",
-  "predictions_unavailable",
-  "bin_unavailable"
-]New value: +[
+  "station_not_found",
+  "invalid_date_range",
+  "date_range_exceeded",
+  "no_predictions",
+  "predictions_unavailable",
+  "bin_unavailable",
+  "upstream_throttled"
+]
  2. Changed24 schema fields changed
    • addedInput schema / properties / bin
      Added value: +{
+  "description": "Depth bin to predict for, taken from the bins[] array on a noaa_marine_find_stations current row (e.g. 15, 10 or 1 at PUG1515). Omit to take the CO-OPS default, which is the shallowest bin. A bin the station does not publish comes back as bin_unavailable naming the bins it does.",
+  "maximum": 9007199254740991,
+  "minimum": -9007199254740991,
+  "type": "integer"
+}
    • addedInput schema / properties / limit
      Added value: +{
+  "description": "Maximum prediction rows to return on this page — max/slack events or 6-minute rows, whichever the interval selects — for a caller that wants fewer than the response budget allows. Omit for the largest page that fits; a value larger than the budget allows does not widen the page.",
+  "maximum": 9007199254740991,
+  "minimum": 1,
+  "type": "integer"
+}
    • addedInput schema / properties / offset
      Added value: +{
+  "default": 0,
+  "description": "Row offset into the matched prediction series — the max/slack events on the MAX_SLACK interval, the 6-minute curve on 6min — for reading a range whose rows do not fit one response. 0 (default) starts at the first row; pass the next_offset from a previous call to continue. An offset past the last row returns an empty page rather than an error.",
+  "maximum": 9007199254740991,
+  "minimum": 0,
+  "type": "integer"
+}
    • changedInput schema / properties / units / description
      Previous value: -"Unit system: english = knots; metric = m/s."New value: +"Unit system: english = knots for speed and feet for the echoed depth; metric = cm/s for speed (not m/s) and meters for the echoed depth."
    • changedOutput schema / anyOf
      Previous value: -[
-  {
-    "not": {
-      "required": [
-        "error"
-      ]
-    },
-    "required": [
-      "station_id",
-      "station_name",
-      "units"
-    ]
-  },
-  {
-    "required": [
-      "error"
-    ]
-  }
-]New value: +[
+  {
+    "not": {
+      "required": [
+        "error"
+      ]
+    },
+    "required": [
+      "station_id",
+      "station_name",
+      "units",
+      "bin",
+      "depth"
+    ]
+  },
+  {
+    "required": [
+      "error"
+    ]
+  }
+]
    • addedOutput schema / properties / bin
      Added value: +{
+  "description": "Depth bin CO-OPS answered with — the requested bin, or its default shallowest bin when none was requested. Null when the response carried no prediction rows.",
+  "type": [
+    "number",
+    "null"
+  ]
+}
    • addedOutput schema / properties / depth
      Added value: +{
+  "description": "Depth of the returned bin, in the requested units: feet under english, meters under metric. Distinct from the bins[].depth on a noaa_marine_find_stations row, which the catalog always publishes in feet. Null when CO-OPS publishes no depth for the bin, or when the response carried no prediction rows.",
+  "type": [
+    "number",
+    "null"
+  ]
+}
    • changedOutput schema / properties / error / properties / data / properties / reason / description
      Previous value: -"Machine-readable failure mode. Declared by this tool: `station_not_found`: CO-OPS returned an error for the station ID — current stations require alphanumeric IDs. `invalid_date_range`: begin_date/end_date is not a real calendar date or begin_date is after end_date `date_range_exceeded`: Requested date range exceeds the 1-year CO-OPS limit. `no_predictions`: Station exists but CO-OPS returned no current-prediction data for the date range. Other values are possible when a failure originates below the handler."New value: +"Machine-readable failure mode. Declared by this tool: `station_not_found`: CO-OPS rejected the station ID as unknown or invalid — current stations require alphanumeric IDs. `invalid_date_range`: begin_date/end_date is not a real calendar date or begin_date is after end_date `date_range_exceeded`: Requested date range exceeds the 1-year CO-OPS limit. `no_predictions`: Station exists but CO-OPS returned no current-prediction data for the requested date range. `predictions_unavailable`: The station is in the current-predictions catalog, but CO-OPS publishes no current predictions for it at any date. `bin_unavailable`: CO-OPS rejected the requested bin because the station publishes no predictions at that bin. Other values are possible when a failure originates below the handler."
    • changedOutput schema / properties / error / properties / data / properties / reason / examples
      Previous value: -[
-  "station_not_found",
-  "invalid_date_range",
-  "date_range_exceeded",
-  "no_predictions"
-]New value: +[
+  "station_not_found",
+  "invalid_date_range",
+  "date_range_exceeded",
+  "no_predictions",
+  "predictions_unavailable",
+  "bin_unavailable"
+]
    • changedOutput schema / properties / events / description
      Previous value: -"Max flood, max ebb, and slack events. Present for MAX_SLACK interval."New value: +"Max flood, max ebb, and slack events — the whole matched series when it fits one response, otherwise the leading page starting at offset. Present for MAX_SLACK interval, and empty when CO-OPS answered with a statement instead of events — read notice for its wording."
    • changedOutput schema / properties / events / items / properties / direction / description
      Previous value: -"True bearing direction in degrees (0–360). Absent for slack events."New value: +"The station's mean flood direction on a flood event and its mean ebb direction on an ebb event, as a true bearing in degrees (0–360). A station constant, not an instantaneous heading. Absent for slack events and wherever CO-OPS reports no mean direction."
    • changedOutput schema / properties / events / items / properties / speed / description
      Previous value: -"Current speed in the requested units. Absent for slack events."New value: +"Peak speed as a non-negative magnitude, in the requested units. Absent when CO-OPS reports no speed for the event, which is the usual case at slack water — though a slack event can carry a small residual speed under metric units."
    • addedOutput schema / properties / next_offset
      Added value: +{
+  "anyOf": [
+    {
+      "maximum": 9007199254740991,
+      "minimum": -9007199254740991,
+      "type": "integer"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "description": "Offset to pass as offset on the next call, or null when this page reaches the last matched row. Absent when the whole matched series was returned."
+}
    • addedOutput schema / properties / notice
      Added value: +{
+  "description": "CO-OPS's own statement about the station when it returned that instead of prediction events — the answer to report, not a failure — or what this page of the prediction series covers and how to reach the next one.",
+  "type": "string"
+}
    • addedOutput schema / properties / page_offset
      Added value: +{
+  "description": "Row offset this page starts at, echoed from the request. Absent when the whole matched series was returned.",
+  "maximum": 9007199254740991,
+  "minimum": -9007199254740991,
+  "type": "integer"
+}
    • changedOutput schema / properties / predictions / description
      Previous value: -"6-minute continuous current predictions. Present for 6min interval."New value: +"6-minute continuous current predictions — the whole curve when it fits one response, otherwise the leading page starting at offset. Present for 6min interval, and empty when CO-OPS answered with a statement instead of a curve — read notice for its wording."
    • changedOutput schema / properties / predictions / items / properties / direction / description
      Previous value: -"True bearing direction in degrees (0–360). Null when CO-OPS does not report direction for this station type."New value: +"The station's mean flood direction on a flood row and its mean ebb direction on an ebb row, as a true bearing in degrees (0–360). A station constant, not an instantaneous heading. Null on a slack row and wherever CO-OPS reports no mean direction."
    • changedOutput schema / properties / predictions / items / properties / speed / description
      Previous value: -"Current speed in the requested units."New value: +"Current speed as a non-negative magnitude, in the requested units."
    • addedOutput schema / properties / predictions / items / properties / type
      Added value: +{
+  "description": "Flow sense at this row, from the sign of the speed CO-OPS predicts: flood (inbound), ebb (outbound), or slack (zero). speed is a non-negative magnitude, so this is what carries which way the water is moving.",
+  "enum": [
+    "flood",
+    "ebb",
+    "slack"
+  ],
+  "type": "string"
+}
    • changedOutput schema / properties / predictions / items / required
      Previous value: -[
-  "time",
-  "speed",
-  "direction"
-]New value: +[
+  "time",
+  "type",
+  "speed",
+  "direction"
+]
    • addedOutput schema / properties / rows_matched
      Added value: +{
+  "description": "Prediction rows the requested date range matched, before the page was cut. Absent when the whole matched series was returned.",
+  "maximum": 9007199254740991,
+  "minimum": -9007199254740991,
+  "type": "integer"
+}
    • addedOutput schema / properties / rows_returned
      Added value: +{
+  "description": "Prediction rows this page carries — the length of events on the MAX_SLACK interval, of predictions on 6min. Absent when the whole matched series was returned.",
+  "maximum": 9007199254740991,
+  "minimum": -9007199254740991,
+  "type": "integer"
+}
    • addedOutput schema / properties / truncated
      Added value: +{
+  "description": "True when this page stops short of the last matched row, so further rows remain at next_offset. False on the final page and on a page past the end. Absent when the whole matched series was returned.",
+  "type": "boolean"
+}
    • changedOutput schema / properties / units / description
      Previous value: -"Speed units: \"english\" (knots) or \"metric\" (m/s)."New value: +"Unit system these values are in: \"english\" (speed in knots, depth in feet) or \"metric\" (speed in cm/s, depth in meters)."
  3. Changed2 schema fields changed
    • removedOutput schema / properties / predictions / items / properties / direction / anyOf
      Removed value: -[
-  {
-    "type": "number"
-  },
-  {
-    "type": "null"
-  }
-]
    • addedOutput schema / properties / predictions / items / properties / direction / type
      Added value: +[
+  "number",
+  "null"
+]
  4. Changed6 schema fields changed
    • changedInput schema / $schema
      Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"
    • addedInput schema / additionalProperties
      Added value: +false
    • changedOutput schema / $schema
      Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"
    • addedOutput schema / anyOf
      Added value: +[
+  {
+    "not": {
+      "required": [
+        "error"
+      ]
+    },
+    "required": [
+      "station_id",
+      "station_name",
+      "units"
+    ]
+  },
+  {
+    "required": [
+      "error"
+    ]
+  }
+]
    • addedOutput schema / properties / error
      Added value: +{
+  "additionalProperties": {},
+  "description": "Present when the call failed. Absent on success.",
+  "properties": {
+    "code": {
+      "description": "JSON-RPC error code for this failure.",
+      "maximum": 9007199254740991,
+      "minimum": -9007199254740991,
+      "type": "integer"
+    },
+    "data": {
+      "additionalProperties": {},
+      "properties": {
+        "reason": {
+          "description": "Machine-readable failure mode. Declared by this tool: `station_not_found`: CO-OPS returned an error for the station ID — current stations require alphanumeric IDs. `invalid_date_range`: begin_date/end_date is not a real calendar date or begin_date is after end_date `date_range_exceeded`: Requested date range exceeds the 1-year CO-OPS limit. `no_predictions`: Station exists but CO-OPS returned no current-prediction data for the date range. Other values are possible when a failure originates below the handler.",
+          "examples": [
+            "station_not_found",
+            "invalid_date_range",
+            "date_range_exceeded",
+            "no_predictions"
+          ],
+          "type": "string"
+        },
+        "recovery": {
+          "additionalProperties": {},
+          "description": "Actionable next step for the caller.",
+          "properties": {
+            "hint": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "hint"
+          ],
+          "type": "object"
+        },
+        "retryable": {
+          "description": "Whether retrying may succeed.",
+          "type": "boolean"
+        }
+      },
+      "type": "object"
+    },
+    "message": {
+      "description": "Human-readable description of what went wrong.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "code",
+    "message"
+  ],
+  "type": "object"
+}
    • removedOutput schema / required
      Removed value: -[
-  "station_id",
-  "station_name",
-  "units"
-]
  5. First observed

TDQS

A5/5.0
Behavior5/5

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

Annotations already declare readOnlyHint, openWorldHint, and idempotentHint, so the description correctly avoids repeating those. It adds valuable behavioral details beyond annotations: the empty-list-with-notice behavior for non-discrete stations, pagination mechanics (rows_matched, rows_returned, next_offset), bin depth echoing, and the 1-year date limit. This is rich behavioral context that the annotations alone do not provide.

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 long but every sentence adds essential information. It is front-loaded with the core purpose, then systematically covers interval, bin, pagination, station IDs, and date limits. No filler or redundancy; each clause earns its place given the tool's complexity.

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?

The description is complete for an agent to call the tool correctly: it covers purpose, parameters, edge cases (empty list, pagination, bin absence), and how to obtain required inputs. The presence of an output schema reduces the need to describe return structure, but the description still explains the pagination fields and bin echo, which is helpful. Nothing critical is missing.

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?

Although schema coverage is 100%, the description significantly enhances parameter understanding. For bin, it explains how to source it from find_stations and the bin_unavailable error. For limit, it clarifies the page-budget interaction. For offset, it explains next_offset chaining. For interval, it clarifies the two modes. For station_id, it reinforces alphanumeric format and acquisition method. These details go well beyond the schema's basic descriptions.

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 clearly states it provides tidal current predictions for a CO-OPS station, listing specific outputs (max flood/ebb speeds, slack times, mean bearings). It explicitly distinguishes itself from the sibling noaa_marine_get_current_profile, which returns observed NDBC measurements. This is a specific verb+resource with clear differentiation.

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

Usage Guidelines5/5

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

The description gives explicit usage context: it contrasts with noaa_marine_get_current_profile for observed currents, explains the MAX_SLACK vs 6min interval choice based on planning vs detailed analysis, and tells how to obtain a valid station ID via noaa_marine_find_stations with types=['current']. It also covers bin selection and date range limits. This is thorough when-to-use guidance with alternatives.

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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