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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), and the description adds real behavioral context on top: the data is triennial so the survey year travels with each figure, and a missing figure is absent and dropped from rankings, never 0. That last point directly prevents a misread of empty results as zero banking access.

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 what is measured, then the usage modes and the caveats. The prose is dense and dash-heavy, but every sentence carries information (source, periodicity, missing-value handling, scope limit); nothing is padding.

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?

Output schema and annotations exist, so return-format and safety details need not be repeated. The description still supplies the interpretive boundaries an agent needs (survey year is attached, cannot answer account-opening eligibility, missing values are dropped), making it complete for this comparison 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 description coverage is 100%, so the schema already documents all four parameters, including that `sort` and `metric` are ignored when `countries` is given. The description restates the metric options and the ranking default but adds no syntax or format detail beyond the schema, 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 precisely what is measured (share of adults 15+ with an account at a bank, other financial institution, or mobile-money provider, plus personal remittances as a share of GDP) and the source (World Bank Global Findex). It also draws the crucial boundary that account ownership means adults CAN bank, not that a newcomer can open an account, which is what a sibling like banking_access or check_residency would answer.

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?

Explicitly describes the two modes: give `countries` (two or more) for a side-by-side, omit it to get the 41-country spine ranked by `metric`. Clear context, but no sibling tool is named as an alternative (e.g. banking_access for a single country), so it stops just short of full routing guidance.

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