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

The description goes beyond annotations by requiring a SnowSure user access token (OAuth) and detailing the trigger semantics for each alert type (e.g., powder is based on observed fresh snow in 24h). This adds useful behavioral context; no contradiction with annotations.

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?

At roughly three sentences, the description is compact yet dense with information, starting with the primary action and using parentheticals to efficiently explain each alert type. Every sentence earns its place without unnecessary verbosity.

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?

The description covers the auth prerequisite, all alert types, and their trigger logic, while schema covers parameter defaults and formats; the presence of an output schema further reduces the need for return-value documentation. This is sufficient for an agent to correctly invoke the tool.

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?

Although the schema already documents all five parameters, the description thoroughly explains the meaning of each 'type' value and clarifies how thresholdCm and windowDays apply differently per type, greatly aiding parameter selection. This is a prime example of description adding value beyond the schema.

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 first sentence, 'Subscribe the signed-in user to snow alerts,' clearly specifies the action (subscribe) and resource (snow alerts), and the enumeration of alert types distinguishes it from siblings like list_alerts and unsubscribe_alerts. The description is precise and leaves no ambiguity about what the tool does.

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 provides clear context on when each alert type is appropriate (e.g., 'forecast' is the proactive watcher) and notes the OAuth requirement, but it does not explicitly contrast with alternative tools such as list_alerts or unsubscribe_alerts. This is a minor omission since the purpose is so distinct, but not fully explicit.

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