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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, so the safety profile is covered. The description adds real value beyond that: it discloses which edge cases are handled (partial period, logging, category W suspended) and that the response includes a filing due date, a link, and an IRS source the agent is told to cite.

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?

Two dense sentences with zero filler, and the core purpose and period are front-loaded before the edge cases and citation instruction. Every clause carries information an agent needs.

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 does the work of describing the return (tax amount, due date, link, source). For a 5-parameter read-only calculator this is nearly complete; only the agricultural/expected-miles suspension mechanics are left unstated.

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 baseline is 3; the description goes slightly beyond by explaining how inputs interact (month of first use drives partial-period proration; suspension categories are evaluated). It still doesn't clarify the 5,000/7,500-mile thresholds the expected_miles parameter feeds, leaving that to 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?

States a specific verb and resource ('Calculates the IRS Form 2290 heavy highway vehicle use tax') plus the exact tax period (July 1 - June 30). The Form 2290/HVUT naming makes it unmistakably distinct from the IFTA siblings (calculate_ifta, get_ifta_rates), so an agent can route without opening any schema.

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 implies context (weight + month of first use, partial-period/logging/suspended cases) but never says when to prefer this over a sibling or what prerequisites apply. No explicit when-not or alternative routing is given, leaving usage inference to the agent.

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