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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered; the description adds real value beyond that by defining the fiscal-year window (Oct-Sep), stating that FY is derived from each opportunity's post_date, and naming the three returned metrics. No return-schema exists, so this disclosure of contents is doing meaningful work.

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?

Front-loaded with the resource and the per-year metrics, then the framing questions. Every sentence carries information, though the two dense sentences could be broken for faster scanning.

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 correctly compensates by naming the three returned metrics and the temporal granularity, and the annotations cover the safety profile. An agent has enough to call this correctly; only the exact edge behavior (e.g. agencies with no postings in a year) is unaddressed.

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%, so both agency_code and years are already fully documented, and the alias behavior is spelled out in the schema. The description's only added semantics is the FY-derivation note, which is marginal; the 3 baseline for high-coverage schemas applies.

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+resource (opportunity-posting trend per federal fiscal year) and enumerates exactly what is computed: opportunity count, total estimated program funding, and average award ceiling. It reads as an aggregate/trend operation, cleanly distinguishable from the search_* and get_* siblings that return individual opportunities.

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?

Frames usage through the questions it answers ('is this agency posting more or fewer opportunities than last year', 'how has this agency's funding trended'), which tells the agent when this aggregate is the right call. It lacks explicit exclusions or a named alternative for the per-opportunity case, so it falls short of a true when/when-not statement.

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