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

Annotations already declare readOnlyHint=true, and the description adds a genuinely non-redundant behavioral fact: 'no data is stored,' which tells the agent the call is stateless and safe to repeat. It stops short of stating accuracy limits or rate limits, so it is not fully exhaustive.

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?

Purpose and inputs are front-loaded in the first sentence, with outputs and the read-only guarantee following. It is dense but every clause carries information; the run-on structure of the first sentence is the only mild weakness.

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 does so thoroughly: annual federal income+SE tax, rough state tax, SE tax, combined total, per-quarter installment, and the pre-filled deep link. Combined with the stated statelessness, an agent has everything needed to call and interpret 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 100%, so the baseline is 3, but the description adds real meaning: netProfit is tied to 'annual Schedule C net profit' and includeQBI is tied to the '§199A QBI deduction,' semantics the schema's terse prose does not spell out. The remaining parameters (filingStatus, taxYear, state) are only restated.

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 (Estimate) and resource (US federal + state quarterly estimated tax payments for a self-employed person), then enumerates the exact inputs it consumes. An agent can immediately tell this is a calculator, clearly distinct from the sibling getPaymentCalendar even without an explicit contrast.

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?

It implies its domain (quarterly estimates for a self-employed filer) and lists the prerequisite inputs, but never states when to use it versus getPaymentCalendar or when it is inappropriate (e.g. W-2 employees, prior-year true-ups). Usage is inferred rather than directed.

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