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NOAA Tides and Currents

by io.github.RyanCardin15
OverviewAdmin

Get Harmonic Constituents

noaa_get_harmonic_constituents
Read-onlyIdempotent

Get the harmonic constituents NOAA uses to compute tide or current predictions at a station — the amplitude, phase, and angular speed of each tidal constituent (M2, S2, N2, K1, O1, ...).

For water-level stations: amplitude (feet/meters), phase_GMT and phase_local (degrees), speed (degrees/hour). For current stations (alphanumeric IDs) constituents are current ellipses (major/minor amplitudes and phases per depth bin — pass bin to filter).

Use for: building custom tide computations, checking a station's dominant constituents (M2 amplitude indicates semidiurnal range), verifying whether a station is harmonically predicted at all. Only reference (R) stations have constituents — subordinate stations use offsets (noaa_get_prediction_offsets).

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
binNoFor current stations: restrict to one depth bin.
unitsNoUnit 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
stationYesStation 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_formatNoOutput format: "markdown" for a readable summary table, "json" for the complete structured payload.markdown

Schema Changelog

Changes observed during successful MCP inspections. Dates show when Glama detected each change.

  1. First observed

TDQS

A4.9/5.0
Behavior5/5

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

Annotations already declare readOnly, openWorld, idempotent, non-destructive. Description adds detailed return values for water-level and current stations, including current ellipses and bin filtering. No contradictions.

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?

Three well-organized paragraphs: general purpose, station-specific details, use cases/limitations. Every sentence adds value. No fluff.

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?

Covers output format (amplitude, phase, speed, ellipses), filtering by bin, and limitation to reference stations. No output schema, but description sufficiently documents return structure. Links to related tools.

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% with good descriptions. Description adds extra context: explains bin is for current stations and units affect feet vs meters. Provides more value than baseline.

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?

Clearly states it gets harmonic constituents for tide/current predictions, lists specific values (amplitude, phase, speed) and distinguishes between station types. Differentiated from sibling noaa_get_prediction_offsets.

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?

Explicitly lists use cases (building custom tide computations, checking dominant constituents) and tells when not to use (subordinate stations → use offsets). Provides alternative tool name.

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

All NOAA Tides and Currents toolsInspect
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