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

Annotations already declare readOnly/idempotent/non-destructive/openWorld, so the safety profile is covered. The description adds a genuine behavioral trait beyond that: 'ERDDAP snaps to the nearest grid cell,' which tells the agent how out-of-grid coordinates are resolved, plus the authority claim about regional resolution.

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 tight sentences, front-loaded with what the tool returns and what it takes, followed by behavior and positioning. The uppercase AUTHORITATIVE is slightly promotional but carries a real routing signal; no wasted clauses otherwise.

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?

No output schema exists, so the description carries some burden for return behavior — it indicates a single value at a point but not units or metadata. Against a fully-documented 7-param schema and annotations covering safety, the definition is otherwise complete for correct 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 baseline is 3; every parameter is already documented in the schema. The description's snapping note lightly reinforces lat/long semantics but adds no format, unit, or dataset-naming detail beyond what the schema supplies.

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 pattern — 'One gridded value at one time, latitude and longitude' — and enumerates the physical variables (temperature, salinity, currents, WRF fields). It implies the grid-vs-table distinction, but never names the sibling ioos_erddap_tabledap, so sibling differentiation is left implicit 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?

It gives a positive reason to reach for this tool ('AUTHORITATIVE for regional-resolution conditions that a global product misses') with a concrete example (PacIOOS ROMS resolving Hawaiian channels). However it offers no exclusion or routing rule against the obvious alternative, ioos_erddap_tabledap, leaving usage implied rather than specified.

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