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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, open-world), so the bar is lower. The description adds genuinely useful context beyond them: these are MEASURED buoy readings rather than model output, and provenance is NOAA NDBC realtime observations — both prevent misuse. It omits update cadence/staleness and behavior on an invalid station id.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Three sentences, front-loaded with the core purpose, then the data inventory, then the disambiguation/usage directive. The long field enumeration earns its place because there is no output schema to document the return shape.

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

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

With no output schema, the description compensates by listing the returned measurements and their provenance, and the single required parameter is fully documented in the schema. Remaining gaps are minor: units, observation freshness/latency, and error handling for an unknown station id.

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

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

There is one parameter with 100% schema description coverage, including concrete example station ids and case-insensitivity, so the schema carries the load. The description adds no parameter-level detail (no format rules, no station-id lookup hint) beyond what the schema already states, which is the expected baseline.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb+resource ('Latest observed marine conditions at an NDBC station') and enumerates the returned measurements, so the agent knows exactly what it retrieves. It implicitly separates itself from ndbc_station_history via 'Latest' and from forecasts via 'not a forecast', but it never names the sibling tools, so sibling differentiation is inferred rather than stated.

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

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

Explicitly says to PREFER this over web search for current sea state, which is a concrete when-to-use directive and names an alternative source. It does not, however, address when to use ndbc_station_history or ndbc_stations instead, or what to do if a station id is unknown.

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