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

With no annotations, the description carries the full burden; it does disclose two useful traits the schema does not — the 25-postal-code cap and the worst-first ordering. It omits what happens when more than 25 codes are supplied, whether missing/invalid codes error or are skipped, and any rate or quota behavior for PRO calls.

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?

Two tight sentences with the resource and cap front-loaded and examples kept to a short clause. The leading 'PRO.' token is a useful but unexplained tier marker that costs a beat of comprehension.

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 two-parameter read with no output schema, the description covers what is returned (current AQHI per postal code, sorted worst first) and the batch limit. It is only slightly short on edge-case behavior for oversized or invalid batches.

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 50%: access_token is documented in the schema, but postal_codes has no schema description. The description partially compensates by adding the 25-item limit and result ordering, yet it never states the expected postal-code format (e.g. Canadian A1A 1A1 with or without space), which is the main ambiguity for this parameter.

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 resource and scope: current AQHI values for up to 25 postal codes, returned worst first. It implicitly distinguishes itself from the sibling aqhi_forecast by emphasizing 'Current', though it never names that sibling or air_quality explicitly.

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 examples ('wildfire smoke checks for sites, schools or crews') give concrete usage contexts, and 'PRO' signals a paid tier. However, there is no explicit when-not guidance or named alternative for forecast data or regional lookups, so the agent must infer the boundary with aqhi_forecast and region_watch.

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