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

Goes well past the annotations (which only declare read-only/idempotent/open-world) by disclosing the on-budget comparison basis, the exclusion of Social Security's off-budget portion, the presence of unified totals alongside, the source (Monthly Treasury Statement, net outlays, nominal dollars), and completeness/adoption flags per year. The missing-resolution degradation path is spelled out, which is exactly the edge-case behavior an agent needs.

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 core comparison and its output shape, then sources and edge cases. Dense but nearly every clause carries information; the parenthetical about Social Security and the dual source attribution are slightly heavier than needed but justified.

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 comparison tool with an output schema, the description supplies the accounting basis, data provenance, completeness flags, and the degenerate-year behavior — everything needed to call it and interpret results correctly. Nothing material is left to inference.

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 coverage is 100%, so all three parameters are already documented, and the description's added meaning is mostly shared context (on-budget basis, nominal dollars) rather than per-parameter guidance. The no-resolution behavior implicitly explains why adopted_only exists, but nothing adds to the syntax or scope of 'function' or 'fiscal_year' beyond the schema.

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?

Names a specific comparison verb+resource: a fiscal year's congressional budget-resolution targets versus what Treasury actually reported, enumerating the exact output dimensions (revenues, outlays, implied deficit, by-function). An agent can distinguish it from budget_resolution_targets or resolution_diff, though the siblings are never named to make the boundary explicit.

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 two concrete trigger phrasings ('how did FY2025 outlays compare to the budget resolution?', 'defense spending vs budget plan') plus an explicit fallback case: a year with no resolution still returns actuals plus a named reason. No explicit when-not or named-alternative routing, which keeps it below a 5.

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