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

Annotations already declare this a safe read (readOnlyHint=true) against a closed domain (openWorldHint=false), so the safety profile is covered. The description adds useful behavioral context by enumerating what is returned (gauge height, discharge, water temperature, flood stage status) — valuable since no output schema exists — but says nothing about data freshness, units, or what happens when a site lacks flood-stage definitions.

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?

A single tight sentence that front-loads the measurements and appends the flood-status enrichment. No filler, no restatement of the tool name.

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?

For a one-parameter read tool with annotations covering safety and no output schema, the description does the important work of enumerating return fields. Minor gaps remain — units (feet vs. cfs), update cadence, and behavior for sites without NWS flood stages — but nothing essential to a correct call is 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?

With a single parameter at 100% schema coverage, the schema already supplies the USGS site-number format and a concrete example. The description only restates 'at a USGS site' and adds no syntax, validation, or edge-case guidance beyond that 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?

The description names a specific verb and resource — 'Latest river gauge height, discharge and water temperature at a USGS site' — and adds the NWS flood stage dimension, so an agent knows exactly what data comes back. It implicitly contrasts with the history sibling via 'Latest' but never names an alternative, keeping it just short of a 5.

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?

Usage is only implied: the word 'Latest' signals a current-conditions lookup versus the historical variant, and the 'USGS site' phrasing hints at the required input domain. There is no explicit statement of when to prefer this over sensors_water_history or sensors_tides, and no prerequisites or failure conditions are given.

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