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

Annotations already establish that this is a read-only, non-destructive, open-world lookup. The description adds meaningful context beyond annotations: the historical-year limitation for paid plans and a 2-credit cost, though it does not discuss rate limits or access requirements in more detail.

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?

The description is compact and front-loads the purpose, but it redundantly repeats the title at the start. Apart from that repetition, each sentence carries useful 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 simple two-parameter lookup with full schema coverage, annotations, and an output schema, the description provides enough context about scope, historical availability, and cost. Return values need not be explained because an output schema exists.

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 both parameters are already documented, including the default previous year and the US-only country restriction. The description adds the historical range starting in 2000 but does not add much else about parameter behavior beyond the schema.

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 states a specific verb and resource: retrieves federal income tax brackets, marginal rates, and standard deductions for US filing statuses. It is clear what the tool returns, though it does not explicitly distinguish itself from the sibling IncomeTaxCalculator.

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 gives a useful constraint that paid plans can query historical tax years back to 2000, but it does not explicitly say when to use this lookup versus IncomeTaxCalculator. Usage is implied by the resource rather than clearly contrasted with alternatives.

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