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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is fully covered structurally. The description adds that the payload is aggregated statistics (mean/percentiles/exceedances/completeness) and names the source system, but says nothing about data latency, coverage limits, or the 1000-row cap behavior.

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?

A single front-loaded sentence with no filler: resource first, then scope, then source attribution. The parenthetical statistics list is dense but all of it earns its place by telling the agent what the rows contain.

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 six parameters, a required set of five, a full output schema, and rich annotations, the description covers what is returned and the geographic/temporal scope adequately. What is missing is minor: guidance on obtaining FIPS/parameter codes and any note on result caps or data freshness.

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% and the schema documents FIPS formats, YYYYMMDD dates, the same-calendar-year constraint, the comma-separated parameter-code list, and the max_rows bound. The description only restates county, calendar year, and pollutants at a high level, adding no syntax or format detail beyond the schema — the expected baseline of 3.

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 resource ('Annual summary air quality statistics') with an explicit scope — per EPA monitor, US county, calendar year, pollutant(s) — and lists the statistics produced (mean, percentiles, exceedances, completeness). It does not explicitly contrast itself with the sibling get_daily_data, though the annual/daily distinction is inferable.

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 only implied: 'annual' versus the sibling daily endpoint, and 'per EPA monitor in a US county' implies the county-scoped use case. There is no explicit when-to-use statement, no prerequisite note (e.g. obtain FIPS via list_counties, codes via list_parameters), and no exclusion of alternatives.

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