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 substantial behavior beyond that: it states which values are stored versus computed, that computed ratios are labeled with formula and source fields so they can be verified, and that a ratio is only produced when both figures fall in the same period of the same record — nothing is estimated.

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?

Two sentences, front-loaded with the resource and its stored/calculated split; the trailing clause about period default is useful but partly duplicates the schema. Dense but nearly every clause carries information.

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 explain the return payload, and it does: per-period margins and ratios, with computed values labeled by formula and source fields. The only missing piece is pagination/volume behavior for a potentially large multi-period response.

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 period and ticker formats are already fully documented in the schema. The description restates the default (latest record, all periods) without adding syntax or meaning beyond the schema's own period description, 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 names a precise resource — profitability margins and balance-sheet ratios — and splits it into stored metrics versus figures calculated on the spot, which an agent can use to tell it apart from get_financials or get_statements. It stops short of naming a sibling or stating an explicit contrast, so it is clear but not sibling-differentiating.

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 only usage information is the default scoping rule ('every period in the latest record by default, or the periods named by period'). There is no guidance on when to choose this tool over get_key_figures, get_financials, or get_segments, and no stated prerequisites.

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