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

Annotations already declare read-only, idempotent, and closed-world, so the safety profile is covered. The description adds model-year anchoring (2026 brackets, 2025–2028 senior deduction), which is useful context. It does not disclose that state tax is only an approximate effective rate or that the output is an estimate rather than filing-grade — gaps the schema hints at but the description ignores.

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?

It is short and front-loaded, but the opening worked example plus the 'not 22%' framing reads as marketing rather than specification, and the trailing URL consumes space without aiding invocation. The core mechanics list does earn its place.

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 read-only calculator with 100% schema coverage and no output schema, most of the burden is already carried by structured fields. Still, the presence of state and stateRate parameters with no explanatory mention in the description leaves an agent unsure whether the result includes state tax or is federal-only.

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 every parameter including the aged enum and stateRate is documented in the schema; baseline is 3. The description adds no parameter meaning beyond the schema, and notably never mentions the state/stateRate inputs even though it otherwise enumerates the tax components.

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?

The description leads with a concrete worked example and names the specific mechanics (IRS brackets, $16,100 standard deduction, $2,200 child credit, 65+ deductions), so the resource is unambiguously US federal income tax. It never states a verb+resource directly and does nothing to distinguish it from siblings like take_home_pay_calculator or salary_calculator, which also return post-tax figures.

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?

There is no when-to-use or when-not-to-use guidance at all. An agent is given no basis for choosing this over take_home_pay_calculator, salary_calculator, or capital_gains_tax_calculator; nothing indicates which income types belong here.

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