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

The annotations already mark this read-only and non-destructive; the description adds valuable behavior beyond that: null values indicate land areas or model gaps, returns are time-indexed hourly values, units are degrees Celsius, and no authentication is required. This gives an agent useful operational context without contradicting the annotations.

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?

The description is compact and front-loaded: the first sentence states the core operation and key parameters, and every subsequent sentence adds useful context such as depth, use cases, null semantics, and source/licensing. There is no filler or repetition of schema content.

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?

Given the rich input schema, output schema, and annotations, the description covers everything needed to correctly invoke the tool: coordinate-based input, time range, units, null behavior, use context, and source. No important operational detail appears missing.

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?

Schema description coverage is 100%, so the schema already documents all four parameters thoroughly. The description adds general context like units and the 16-day horizon but does not materially expand on what the parameter schemas already say, so the baseline score of 3 is appropriate.

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?

The description clearly states a specific verb and resource: it forecasts hourly sea surface temperature at an ocean coordinate in degrees Celsius for up to 16 days. It names the phenomenon (SST, ~1m depth) and distinguishes itself from sibling marine tools by its specific target variable.

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?

The description gives clear use contexts like coral bleaching risk assessment, fishery management, and climate monitoring, so an agent can infer when SST data is relevant. However, it does not explicitly mention when not to use this tool or how it compares to sibling tools such as marine.ocean.forecast, marine.ocean.swell, or marine.ocean.waves.

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