noaa-tidesandcurrents-mcp

Get Station Datums

noaa_get_station_datums

Read-onlyIdempotent

Retrieve accepted tidal datum elevations for a NOAA station, including MHHW, MHW, MLLW, and NAVD88. Check supported datums or convert heights between references.

Instructions

Get the accepted tidal datum values for a station: the elevations of MHHW, MHW, MTL, MSL, DTL, MLW, MLLW, STND, NAVD88 (where computed), plus GT (great diurnal range), MN (mean range), LAT/HAT (lowest/highest astronomical tide), and the station's historical extreme min/max water levels with dates.

epoch "current" returns the present National Tidal Datum Epoch (1983–2001) values; "superseded" returns the prior epoch's values (useful for historical comparisons — not all stations have one).

All values share one reference zero (the station datum), so datum-to-datum conversion is subtraction: height_above_MLLW = height_above_MSL + (MSL − MLLW). Use this tool to (1) check which datums a station supports before requesting data, and (2) convert heights between datums.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`epoch`	No	"current" = present NTDE (1983–2001); "superseded" = prior epoch values.	current
`units`	No	Unit system. english: feet, °F, knots (wind AND currents), nautical miles. metric: meters, °C, m/s for wind but cm/s for currents, kilometers. Air pressure is millibars and salinity is PSU in BOTH systems.	english
`station`	Yes	Station ID. Water-level/met stations use 7-digit numeric IDs (e.g. "9414290" San Francisco); current stations use alphanumeric IDs (e.g. "cb0102"). Find stations with noaa_search_stations or noaa_find_nearest_stations.
`response_format`	No	Output format: "markdown" for a readable summary table, "json" for the complete structured payload.	markdown

Output Schema

TableJSON Schema

Name	Required	Description	Default
`_response`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Addedv1.0.1Oct 5, 2026

TDQS

A4.4/5.0

Behavior4/5

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

Annotations already cover the read-only/idempotent safety profile, and the description adds genuine value beyond them: the shared station-datum reference zero, the datum-to-datum subtraction formula, the caveat that 'superseded' is not available for all stations, and that historical extreme min/max include dates.

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?

Front-loaded with the core purpose and scoped with a colon into the datum list; the long enumeration is justified because it tells the agent exactly what is retrievable. The clause structure is dense but no sentence is wasted.

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?

With an output schema present, return-format details are not required, and the description still covers the key behaviors an agent needs: epoch semantics, station-datum reference zero, conversion formula, and availability caveats. Nothing material is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so the baseline is 3; the description still adds meaning, notably the semantics of epoch ('current' = present NTDE 1983–2001; 'superseded' = prior epoch) and the caveat that not all stations have a superseded epoch, which goes beyond the schema's terse enum note.

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?

Specific verb+resource ('get the accepted tidal datum values for a station') with an explicit enumeration of the datums returned (MHHW, MHW, MTL, MSL, etc.). This distinguishes it clearly from siblings like noaa_get_station_info (metadata) and noaa_get_water_levels (observations).

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

Usage Guidelines4/5

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

Gives two explicit use cases: (1) check which datums a station supports before requesting data, and (2) convert heights between datums. Clear context, though it does not name a specific alternative tool or state exclusions (e.g., when to use harmonic constituents or prediction offsets instead).

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