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

Goes well beyond the readOnlyHint/openWorldHint annotations: it discloses the free-vs-Pro gating on the multi-year `series`, the `locked` marker for gated data, and the critical sparse-station behavior that a missing pollutant is a gap rather than clean air. These are exactly the non-obvious traits an agent needs to avoid misreporting.

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?

Four dense sentences, front-loaded with what is measured and where before moving to the paywall and coverage caveats. Every sentence is informative, though the place-type enumeration marginally overlaps with the schema and purpose statement.

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 still explains the shape of the return (a verdict, its benchmarks, the station, a locked `series`, and gap reporting), so an agent knows both the entitlement behavior and how to interpret missing pollutants. Nothing material is missing for a 2-parameter read tool.

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%, including the municipality-median vs postal-area-nearest-station semantics, so the schema already carries the parameter meaning. The description only restates the place-type choice, adding no syntax or format detail beyond what the schema provides.

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 verb (retrieve measured annual-mean air quality), names the exact pollutants, the geography (Finnish postal area or municipality) and the data sources. This is clearly distinguishable from siblings like get_area_report or compare_areas, which are broader or comparative.

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?

Gives clear usage context via the example question ("is the air clean in Vantaa?") and explains the sparse-coverage caveat that governs how to interpret results. It does not, however, explicitly name an alternative tool or state when to prefer get_area_report or compare_areas over this one.

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