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

With no annotations, the description carries the full burden of behavioral disclosure. It explicitly reveals the return structure ('a summary with plain-English health assessment... raw aqi and who_compliance data') and even directs presentation order. It does not discuss error handling or authentication, but for a read-only data tool, the key behaviors are transparently covered.

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?

The description is front-loaded with the core purpose, then logically breaks down returns and arguments. Every sentence provides necessary information: the health-summary focus, the presentation instruction, and the parameter formats. It is concise despite having multiple sections—no fluff or repetition.

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 tool with no output schema and no annotations, the description does a good job explaining return values and parameters, making it largely complete. However, it omits edge-case behavior (e.g., invalid location, missing data) and any rate limits or prerequisites, so it leaves a small but non-critical gap.

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 0%, so the description must compensate—and it does thoroughly. For each parameter it explains the acceptable format and choices: location as 'Postcode, place name, or "lat,lon"', index with three AQI systems and a default, period with four time frames. This goes well beyond the schema's bare type/default information.

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 clearly states the tool's purpose: 'Get an AQI assessment with health advice and WHO compliance check.' This specific verb+resource combination distinguishes it from sibling tools like get_current_aq and assess_location_aq, which focus on raw readings or location assessment rather than a combined health summary.

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 implies when to use the tool—whenever an AQI summary with health advice and WHO compliance context is needed—and instructs the agent to 'Present the summary to users first.' However, it does not explicitly mention when not to use it or name alternative sibling tools, so it stops short of a full exclusionary guideline.

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