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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), and the description adds real operational context: the custodial-attribution caveat, snapshot-vintage fallback, bounded pagination, and inclusion of exact source lines and hashes. It does not state rate limits or failure modes, but for a read-only ranking tool this is substantial added context.

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?

Opens with the core question, then layers scope, exclusions, and return characteristics in a tight sequence with no filler. It is denser than average but every clause carries information; only the enumeration of return fields is slightly list-like.

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?

There is no output schema, so the description carries the return burden and does so: pagination bounds, USD millions units, exact source lines, hashes, vintage, and the attribution caveat. Combined with full schema coverage and clear annotations, an agent has everything needed to call it correctly.

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 the baseline is 3, but the description adds meaning beyond the schema for two parameters: include_historical_aggregates is explained as discontinued publisher aggregates (e.g., Oil Exporters) in older rankings, and the month-omitted fallback to the hosted snapshot vintage is not in the schema. Limit/offset/response_format behavior is left to 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?

States a specific verb (ranks) and resource (named major foreign Treasury holders in a specified month) and immediately scopes what is ranked and what is excluded. An agent can distinguish it from treasury_tic_compare_holders, treasury_tic_find_holders, treasury_tic_holder_history, and treasury_tic_official_share without opening any schema.

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?

Gives clear inclusion/exclusion rules (Grand Total, All Other, foreign-official memo rows excluded; historical aggregates excluded unless requested) and states the default behavior when month is omitted. It does not explicitly name which sibling to use instead for aggregate or official-flow questions, so it stops short of a full when/when-not routing statement.

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