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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds real value beyond that by naming the authoritative rule set (Rev. Procs. 2024-40, 2025-32) and disclosing what is returned (taxable gifts, Form 709 requirement, lifetime exemption used/left, gift tax due). It does not mention edge-case behavior for amounts above the lifetime exemption or how prior_taxable_gifts interacts, which keeps it from a 5.

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?

The verb and year range are front-loaded, and the second sentence cleanly enumerates return values, so structure is sound. The middle clause is dense with statutory dollar figures and citation numbers that partly duplicate what the tool computes anyway, making it slightly heavier than needed.

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?

No output schema exists, so the description carries the return-value burden and does so explicitly (taxable gifts, Form 709, exemption used/left, gift tax due). With all 7 parameters covered at 100% in the schema and the governing rules and defaults named, an agent has everything needed to call and interpret this tool.

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?

With 100% schema coverage, the baseline is 3, but the description genuinely enriches semantics: it explains that amounts are per recipient, that gift_splitting doubles the exclusion to $38,000 via sec. 2513, and that spouse_citizen selects between the unlimited marital deduction and the $190k/$194k non-citizen exclusion. It does not clarify how prior_taxable_gifts feeds the lifetime exemption calculation, so it stops short of 5.

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 ('Checks a gift against the federal gift tax rules for a year') and enumerates the exact rules applied (annual exclusion, sec. 2513 splitting, marital deduction, non-citizen spouse exclusion). Sibling tools like calculate_estate_tax and get_exemption_amounts are not named or implicitly contrasted, so differentiation is by inference rather than explicit statement.

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?

The description's phrasing ('Checks a gift') implies usage for a single-gift scenario with per-recipient amounts, but it never states when to prefer this over get_exemption_amounts or compare_years. No exclusions, prerequisites, or alternative-selection logic are provided, so usage is only implied by the parameter shape.

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