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

With no annotations, the description carries the full burden of disclosure. It clearly details the structure of the output: a 'summary' with count, status, and type explanations, and a 'monitors' list with metadata. It also adds a behavioral directive to present the summary first, which is valuable context beyond a generic 'list' operation.

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 well-structured: a one-sentence summary first, then output details, then an Args section. Every sentence adds meaningful information without repetition or fluff. It is concise and front-loaded, making it easy for an agent to quickly grasp the tool's function.

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 tool has three parameters and no output schema, so the description must cover both inputs and outputs. It explains the summary and monitors list sufficiently for an agent to handle the result correctly. However, it leaves 'full metadata' vague and doesn't mention ordering or edge-case behavior, making it strong but not exhaustive.

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?

The schema has zero descriptions (0% coverage), and the description fully compensates by explaining each parameter: location accepts postcode, place name, or 'lat,lon'; radius_km is the search radius with default 5.0; sources is an optional filter with concrete examples. This provides essential value that the schema lacks.

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 opens with a precise, specific action: 'List air quality monitoring sites near a location, with context.' It clearly identifies the resource (monitoring sites), the scope (near a location), and what is returned (summary and monitors list). This distinguishes it from sibling tools that deal with measurements or historical data.

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 a clear use case—finding monitoring sites near a location—but does not explicitly contrast with sibling tools like get_current_aq or get_aqi_summary. It does give a practical instruction ('Present the summary to users first') but lacks explicit alternatives or exclusionary guidance.

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