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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description goes further by disclosing the data boundary (available from 2022) and the shape of the answer (cents per mile for business/medical/charity, covering period, announcing IRS notice, verification date), which is context annotations cannot carry.

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 trigger and example queries, then the parameter, then the return contents, then the limits. It is on the long side and the three example phrasings are somewhat redundant, but every sentence carries information and nothing is buried.

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?

An output schema exists, so return values need not be explained, yet the description still summarizes them; the mutation/auth profile is carried by annotations. Coverage of when to call it, how to call it and the data range is complete for a single-parameter read tool.

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% and the single 'date' property already documents the YYYY-MM-DD format and that the rate in force on that day applies. The description restates the same semantics ('Pass the date (YYYY-MM-DD)'), adding examples of use but no new format or constraint information, so the 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 ('look up the IRS standard mileage rate on a day') and pins the scope to a single date's in-force rate. It also explicitly disclaims what it does not do ('does not add up trips or compute a deduction'), which cleanly separates it from the tax-calculation siblings.

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?

Gives concrete when-to-use triggers with three paraphrased user phrasings and a boundary ('rates are available from 1 January 2022'), plus the when-not ('does not add up trips or compute a deduction'). It never names an alternative tool (e.g. get_tax_parameters or estimate_federal_tax), so routing between siblings is left to inference.

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