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

Beyond the annotations (read-only, idempotent, closed-world, non-destructive), the description adds substantial behavior: table names vary by company and are echoed as the record names them, figures are in actual dollars rather than millions, shares are split-adjusted, foreign issuers are converted to USD, and a no-segmentation company returns a message listing the tables it does have.

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 core purpose is front-loaded in the first clause, and the dense parentheticals each carry distinct information (what each breakdown covers). It is a single long, somewhat run-on paragraph, but little of it is filler given the breadth of the tool.

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 carries the return-value burden and does so: it names the three result sets, the period coverage, unit conventions, and the empty-result behavior. Nothing an agent needs to invoke and interpret this read-only tool is missing.

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 on top: it confirms the breakdown default of 'all', ties `period` to the company's own fiscal years and the latest-record default, and specifies the currency/adjustment conventions of the returned figures. This goes beyond restating 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?

The description states a precise verb+resource - how a company's results split as reported - and enumerates the three concrete breakdowns (segments, revenue_by_product, revenue_by_geography) with real-world examples (NVIDIA's Data Center, Apple's iPhone and Services). An agent can tell exactly what data comes back, though no sibling tool (e.g. get_financials, get_statements) is named to disambiguate the boundary.

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 sets the operative defaults ('Default: all three' breakdowns; every period in the latest record unless `period` names others) and describes the fallback when a company reports no segmentation. That gives clear context for calling it, but there is no explicit when-to-use/when-not guidance relative to the sibling financial-statement tools.

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