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

Annotations already cover read-only, idempotent, and non-destructive behavior. The description adds valuable behavioral context by disclosing that ERDDAP snaps to the nearest grid cell and that approximate positions are acceptable, plus provenance information about NOAA's own gridded product.

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?

Two sentences, each earning its place: the first states the core function, the second adds behavioral and provenance context. It is front-loaded and free of filler.

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?

The description covers purpose, snapping behavior, and data provenance, while the schema covers all parameters. With no output schema, it could be slightly more explicit about the return format or units, but the 'one gridded value' phrasing gives a sufficient mental model for invocation.

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 every parameter. The description adds the useful note that approximate latitude/longitude is fine due to grid-cell snapping, but it does not add substantial parameter-level meaning beyond the schema.

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 identifies the resource (a CoastWatch gridded product) and the output shape (one value at a given time, latitude, and longitude), and it contrasts with station-based interpolation. However, it uses a noun phrase rather than an explicit verb like 'get' or 'retrieve', and it does not name sibling tools.

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?

It explicitly frames the intended use case ('AUTHORITATIVE for how warm was the ocean at this spot on this date') and states what the tool is not ('not from an interpolation of nearby station reports'). It does not name alternatives such as noaa_coastwatch_tabledap, but the context is clear.

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