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

With no annotations, the description carries the full burden and does well: it discloses that data is provisional USGS, that no API key is needed, that it deliberately omits a derived flood-risk score and why, and that it is real-time rather than static/historical. It stops short of covering failure behavior (no gauge found) or rate limits, but the disclosure is unusually honest and useful.

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?

Front-loads the core purpose and keeps most sentences earning their place (no key, provisional data). Minor noise comes from the catalog self-reference and the full return-field enumeration, which is somewhat redundant given an output schema exists.

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?

Good coverage of data source, scope, and auth, and it needn't explain return values since an output schema exists. The notable gap is parameter context: with 0% schema coverage, an agent still lacks coordinate conventions (order/CRS) needed to invoke it correctly.

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 0% (lat/lon have no descriptions), so the description must compensate, but it only says 'to a point' without specifying coordinate order, CRS, or units. The two required parameters remain semantically underspecified for an agent to call confidently.

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: the nearest USGS real-time stream/river gauge to a point, returning live streamflow (ft3/s) and gauge height (ft). It even distinguishes itself from siblings by noting it is the 'First real-time (not static/historical) primitive in the catalog,' so an agent can tell what it is and what it isn't.

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?

Provides a scoping condition ('US rivers and streams only') and frames the tool as the live/real-time option, which implies when to reach for it. However, it names no alternative sibling (e.g., get_terrain_profile or historical climate tools) and states no explicit when-not to use it.

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