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

Annotations already declare read-only, non-destructive, open-world, so the safety burden is lifted. The description still adds real behavior the annotations cannot convey: fiscal_year silently resolves to the last completed fiscal year rather than the current one, with the rationale, and the response always echoes fiscal_year. Pagination and sorting behavior are left unstated.

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 purpose, then the domain definition, then the operational caveat — a sensible ordering with short paragraphs. The October 1 aside is slightly chatty but directly justifies the default, so it earns its place.

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?

Output schema exists, so return values need not be described. But with six parameters and zero schema description coverage, an agent still lacks guidance on what sort/order/limit do in this context (e.g., whether obligated_amount vs gross_outlay_amount changes meaning) — a meaningful gap for a list tool with pagination.

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 0%, so the description must compensate, and it does so only for fiscal_year — explaining that null resolves to the last completed FY, which goes beyond the schema's bare default of null. The other five parameters (toptier_code, page, limit, sort, order) get no semantic treatment, and the sort enum's meaning is never clarified.

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 the object class breakdown') and immediately defines the domain term: what an agency spends money on, with concrete OMB examples. Scoped to agency level via the toptier_code requirement, which distinguishes it from get_federal_account_object_classes without needing the sibling named.

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?

'Useful for understanding what types of expenditures an agency makes' gives a clear use case, and the fiscal-year note tells the agent what to expect by default. It does not state when to prefer the federal-account-level sibling or when this breakdown is the wrong lens, so exclusions are absent.

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