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

Annotations already establish read-only, idempotent, non-destructive behavior; the description adds the useful limitation that demo mode only supports 2026 and standard filing statuses. This is genuine behavioral context beyond the annotations, though it does not describe output details or error behavior.

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?

One sentence states the core action and a second sentence states the key limitation; there is no filler. The most identifying information is front-loaded.

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 read-only lookup with two parameters this is minimally adequate, but there is no output schema and the description does not explain what a 'bracket reference row' contains (rates, thresholds, etc.). An agent could call it correctly but would not know the exact return shape or accepted filing status values.

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 0%, so the description must compensate, but it only narrows the year to 2026 and vaguely refers to 'standard filing statuses.' It does not list the accepted filing_status strings or the valid year range, leaving the agent to guess at parameter values beyond the defaults.

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 uses a specific verb and resource: 'Return federal tax bracket reference rows.' The qualifier 'federal' and 'reference rows' clearly separates it from state-bracket or calculation tools among siblings, so an agent can tell what it does.

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 opening phrase gives clear context for when this tool is relevant (federal bracket reference data), and the demo-mode sentence communicates the constraint that only 2026 and standard filing statuses are supported. It does not explicitly name alternatives like tax_state_brackets or tax_calculate, so it stops short of full when/when-not guidance.

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