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

ReadOnlyHint is true and the description does not contradict it (says 'get', a read operation). Beyond the annotation, it discloses a key behavior: automatic nearest-station resolution when coordinates are provided. This adds meaningful context beyond the schema and annotations, justifying a 4.

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 sentence that front-loads the core purpose and then covers both input methods without any redundant words. Every phrase contributes value, and it is immediately scannable.

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 simple read-only tool with a full output schema and 100% parameter documentation, the description covers the essential usage: giving coordinates or a station ID. It does not explicitly mention that station_id overrides coordinates (though the schema does) or that only one input method should be used, but that is covered structurally. Overall, an agent has enough to call 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 coverage is 100% and each parameter already has a clear description (e.g., latitude says 'for automatic station resolution'). The description adds no new parameter semantics beyond an example station ID and a pointer to nws_find_stations, which the schema already implies. Baseline 3 is appropriate when the schema fully documents parameters.

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 the specific verb 'Get' and resource 'current weather observations', with the parenthetical 'actual measured conditions' clearly differentiating from forecast tools. The description also names both input methods (coordinates and station ID), making its scope unambiguous.

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 implies when to use it (for current measured conditions rather than forecasts) and references nws_find_stations for station ID discovery, but does not explicitly contrast with sibling tools like nws_get_forecast or state when *not* to use it. The context is clear, but explicit alternatives are missing, so it falls short of a 5.

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