Singapore haze (PSI / PM2.5)

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

With no annotations, the description carries the full burden. It usefully discloses provenance (NEA via data.gov.sg) and freshness ('refreshed hourly'), plus the fact that all five regions are returned. It omits any auth requirements, failure behavior when geolocation or IP lookup fails, and defaults beyond what the schema states.

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 sentences, zero filler, with the scope (nearest PSI region) front-loaded and provenance/freshness trailing. Every clause earns its place.

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?

There is no output schema, so the description correctly enumerates the returned values (24-hr PSI, 1-hr PM2.5, 24-hr PM2.5/PM10, band, advisory, all five regions). No annotations exist, so more on permissions or geolocation fallback would close the remaining gap, but for a read-only atmospheric data lookup this is close to complete.

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 ip, lat, lon, lang, and region with enums and defaults. The description adds nothing parameter-specific, 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 names a specific verb+resource ('Current haze for the caller's nearest PSI region') and enumerates the returned metrics, so the tool's function is unambiguous. It never names or contrasts against siblings (weather_now, get_rain, get_forecast, locate_me), which is the only thing separating it from a 5.

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?

Usage is implied by 'current haze for the caller's nearest PSI region' but there is no explicit when-to-use, when-not, or alternative routing (e.g., vs weather_now or locate_me for geolocation). An agent must infer the context from the purpose statement alone.

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