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

Annotations already cover read-only, idempotent, non-destructive, closed-world behavior, so the bar is lower. The description still adds real value by disclosing the two exact formulas (including the 92.35% x 15.3% self-employment tax breakdown), the supported period granularities, and the important caveat that results are an estimate, not tax advice.

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 core formula, then supporting detail, then the disclaimer in the final clause. Fairly dense but every clause carries information; only the URL reference is arguably non-essential.

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?

The tool is a simple three-parameter pure calculation and an output schema exists, so return-value explanation is unnecessary. The description supplies both formulas, period scope, and the estimate disclaimer, leaving little an agent would need to look up. A minor gap is the absence of an example or note on how rounding/currency 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 all three parameters are already documented including the period enum and percent units. The description reinforces that percent is applied to per-period profit and that results are expressed per month/quarter/year, but adds no format or unit detail beyond the schema. Baseline 3 applies.

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 ('Estimates how much of a self-employed profit to set aside for taxes') and immediately gives the exact arithmetic, so the agent knows precisely what is computed rather than just the topic. Clearly distinguishable from the arithmetic-style siblings like calculate_loan_payoff or calculate_price_per_job.

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 rather than stated: the agent must infer that this applies to self-employed profit estimated for a month, quarter or year. There is no explicit when-to-use/when-not or named alternative among the calculation siblings. The 'not tax advice' caveat frames the output's authority but is not a usage rule.

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