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

Annotations already declare the operation is read-only, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely useful behavioral facts beyond that: the unit contract ('Input dollars; result integer cents') and the fact that rules are 'bundled 2026' rules, telling the agent the tax model is a fixed vintage rather than live data.

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?

Three short sentences, no filler, and the most decision-relevant clause (what it computes) is front-loaded ahead of the unit and rule-vintage details. Nothing could be cut without losing information.

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 six-parameter tool with no output schema, the description does cover units and tax-rule vintage, which helps. It does not clarify whether the returned value is the net payout, the tax amount, or a breakdown including state and local withholding, and it omits the modeling limitations (only NYC/Yonkers localities, no cross-state claims) that a caller would want before trusting the result.

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 67%, and the description reinforces the critical dollars-in/cents-out convention for the 'prize' parameter and the result. But it says nothing about 'game', 'status', 'locality' or 'otherIncome', so the remaining documented gap is not compensated. Baseline 3 for mid coverage is appropriate.

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+resource pair: estimate taxes and withholding on a known lottery cash prize. This cleanly separates it from calculate_lottery_odds, calculate_pool_share and compare_lump_sum_annuity, though those siblings are never named explicitly. An agent can identify the tool's domain without opening the 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 phrase 'on a known lottery cash prize' implies the precondition that the prize amount is already determined, which hints at sequencing after a prize is known. However, it never states when not to use it or points to a sibling for related questions (odds, pool sharing, annuity comparison). Usage is only implied.

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