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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint, and destructiveHint=false, so the safety profile is fully covered. The description only adds the provenance note ('Source: US EPA AQS'), which is minor context; it says nothing about result size, ordering, or coverage gaps beyond what the output schema supplies.

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?

Three short sentences, front-loaded with the verb and resource, then examples, then downstream usage. No filler, nothing repeated from structured fields.

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 reference list with one optional enum parameter, an existing output schema, and full annotations, the description covers everything an agent needs: what is returned, what it is for, and where to use it. Nothing material is missing.

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%: the single parameter_class is documented with its full enum and a stated default of CRITERIA. The description only restates 'for a parameter class', adding no syntax or enum detail, so the baseline 3 is appropriate.

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 and resource ('List EPA Air Quality System parameter codes') and makes the deliverable concrete with examples (PM2.5 88101, ozone 44201). An agent can distinguish this reference-lookup tool from the sibling data tools (get_annual_data, get_daily_data, get_monitors) without opening the schema.

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?

'Use the codes with the other epa-aqs tools' tells the agent why this tool exists and how its output feeds the rest of the epa-aqs family. It gives clear context but no explicit when-not or alternative-selection rule (there is no competing sibling for this list function).

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