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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, open-world), so the bar is lower; the description still adds that results are sorted by total, that they include complete-corpus provenance and tract-vintage/cycle warnings, and that only the final 2018 cycle is covered. These are meaningful behavioral traits beyond the annotations.

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?

Three sentences, front-loaded with the core comparison question, then comparison dimensions, then caveats. Slightly dense with the negative-coverage list, but every clause carries scope-relevant information and nothing reads as filler.

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?

With no output schema, the description must convey what comes back, and it does: sorted designation counts broken into total/LIC/Non-LIC Contiguous/covered-county buckets, plus provenance and vintage warnings. Combined with annotation coverage, an agent has enough to call it correctly; only the response_format behavior is left entirely to the schema.

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 100%, so the schema already documents both parameters fully (including the 2-10 item bounds and the markdown/json enum). The description reinforces that jurisdictions are state/territory selectors that get resolved exactly, but adds no syntax or format detail the schema lacks, so the baseline of 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?

The description states a specific verb (compares) plus resource (final 2018-cycle QOZ designations) and scope (2-10 states/territories), and enumerates the comparison dimensions (total, LIC, Non-LIC Contiguous, covered county counts). It is readily distinguishable from sibling tools such as opportunity_zones_lookup_designation and opportunity_zones_summarize_designations because it is explicitly the multi-jurisdiction comparison.

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 frames the exact question the tool answers ('which of 2-10 requested states/territories has more...') and lists what it does NOT cover (investment quality, land area, population, current eligibility, 2027 cycle), which implicitly routes the agent away from misusing it. However, it does not name the alternative sibling tool to use for single-jurisdiction lookups or summaries, so it stops short of explicit 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.