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

Annotations already declare readOnly/idempotent/openWorld/non-destructive, so the description is free to add the harder context and does: `data.current` distinguishes station observation, model estimate, and forecast hour, `data.alerts.status` distinguishes a verified "no alerts" from an unchecked one, and results carry sources, data age, and cache status. These are trust-critical traits no annotation conveys.

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-loaded with the core purpose and scoped tightly, with no filler paragraphs. It runs long across several clauses and quote-heavy examples, but each sentence carries distinct routing or behavioral information.

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?

With no output schema, the description compensates by explaining the meaning of key response fields (`data.current`, `data.alerts.status`) and the provenance/age/cache behavior of answers. An agent knows what to expect back and how much to trust it.

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 100%, so the schema already documents hours, units, location, latitude, and longitude. The description adds no parameter-level detail beyond that, which matches the baseline 3 when structured fields do the heavy lifting.

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 gives a specific verb+resource (plain-language weather for a place) and enumerates exactly what the answer contains: one sentence, current conditions, 24 hours, 7 days, alerts. It also distinguishes itself from the nearest sibling by naming outdoor_activity_weather and contrasting "what is it?" with "should I?".

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?

It supplies trigger phrases ("what's the weather", "do I need a jacket", "is it going to rain") and an explicit exclusion with a named alternative for outdoor-decision queries. This is exactly the when/when-not/alternative structure the rubric rewards.

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