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

Annotations already declare this a pure, idempotent, non-destructive read, so the safety burden is lifted; the description instead adds computational behavior: the dollar-for-dollar phase-out above the threshold, application of the business income limit, and reporting of the carryover. It also honestly discloses the tool's own limitation for 2027. It stops short of describing the response shape or what happens when the phase-out zeroes the deduction.

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 verb and the dollar thresholds that matter most, and every sentence carries content (limits, income limit, carryover, 2027 gap). The parenthetical citations are verbose, though defensible for a tax-calculation tool where authority matters.

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 carries the return-value burden, and it does signal the key outputs (deduction amount subject to phase-out, income limit, carryover) plus the 2027 out-of-range behavior. It is not fully complete: an agent cannot predict the exact response fields or how a fully phased-out deduction is reported.

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 the schema already documents all four parameters, making 3 the baseline. The description adds only marginal semantic value, notably that business_taxable_income drives the income limit and that the phase-out depends on total property cost — useful linkages, but not format, units, or edge-case detail 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?

A specific verb and resource ("Calculates the Section 179 expense deduction as Form 4562 Part I does") leaves no ambiguity about what is computed, and the cited legal authorities anchor it precisely. It never names its siblings (calculate_bonus_depreciation, get_vehicle_depreciation_limits), so an agent must rely on domain knowledge of Section 179 vs. bonus depreciation to route correctly.

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 implied by the domain and by the year coverage stated (2025-2026, with 2027 explicitly unavailable as of 2026-11-02), which is a useful boundary. But there is no explicit when-to-use / when-not guidance, no mention of the alternative depreciation tools, and no stated prerequisites such as needing the property placed in service in the year.

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