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

With no annotations, the description carries the behavioral burden. It discloses that this is a read operation ('Get'), US-only coverage, NWS source, and the response contents (named periods, temperature, wind, short/detailed text). It does not mention limitations such as exact forecast horizon or units, but the essential behavior is transparent.

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 short sentences, each earning its place: core action, expected return shape, and routing hint. No redundant filler or repetition of schema details.

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 low-complexity, read-only forecast tool with three parameters and no nested objects, the description plus fully covered schema gives an agent everything needed to select and call it correctly. The return content is described even though no output schema exists.

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%, so lat/lon already have decimal-degree and coverage context, and hourly has a default and behavior note. The description adds no parameter-level detail beyond the schema, so the baseline 3 applies.

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 ('Get'), resource ('multi-day weather forecast'), and required inputs (US lat/lon), and identifies the data source (National Weather Service). The return summary (named periods with temperature, wind, and short/detailed forecast) makes it easy to distinguish from siblings like weather_current and weather_alerts.

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?

Gives explicit routing guidance: use geocode first if only an address is available, which clearly states an important precondition. It does not explicitly name weather_current as the alternative for current conditions, though 'multi-day forecast' implies the distinction.

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