Get AGI distribution by ZIP

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

Beyond the annotations (readOnlyHint=true, openWorldHint=true), the description discloses a critical behavioral nuance: 'a bracket showing 0 may be IRS-suppressed (<20 returns in that cell) rather than truly empty', and that this can cause other brackets' shares to be 'slightly overstated'. It also clearly enumerates what is returned (number of returns, total AGI, and share) which goes beyond the annotation hints.

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 front-loaded with a clear purpose statement, then compactly details return contents and the suppression caveat in a separate paragraph. Every sentence adds value, and the note is placed at the end to avoid obscuring the main behavior. No fluff or repetition.

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?

Given an output schema exists, the description doesn't need to spell out every return field, but it does anyway by naming the six brackets and listing the metrics returned. It also covers edge behavior (IRS suppression) and the impact on other shares. This makes the tool fully understandable in context, with no major gaps.

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?

With schema description coverage at 0%, the description compensates by explaining `zip_code` as 'a 5-digit US ZIP'. This is minimally sufficient for a single-parameter tool. It doesn't clarify whether a numeric string with leading zeros is expected, but the 5-digit US ZIP description covers the core semantic need.

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 clearly states the tool 'Returns the income distribution of a ZIP across the six IRS AGI brackets', naming a specific resource (ZIP income distribution) and the six bracket breakdown. It distinguishes itself from sibling tools by emphasizing 'the income *shape* of a ZIP — what a single median can't show', which contrasts with likely aggregate income tools.

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 description provides clear context on when to use the tool: when the full distribution shape is needed rather than a single median. It doesn't explicitly name alternative tools for other use cases, but the phrase 'what a single median can't show' implies a comparison and sets expectations. The IRS suppression note also helps the user interpret results correctly, which is part of guiding appropriate use.

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