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

Annotations already declare readOnlyHint=true, openWorldHint=true and destructiveHint=false, so safety behavior is covered. The description adds provenance and a real constraint (data comes only from the latest 10-K, segment dimensions are absent from companyfacts), but says nothing about what happens when a company reports no segments or when parsing fails.

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?

One sentence, front-loaded with what is returned, with provenance and the sibling distinction packed into a tight parenthetical. No 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?

For a read-only retrieval tool with no output schema, the description covers what data comes back and where it comes from, but not the shape of the result (per-period vs latest-only, segment-level rows) or empty-result behavior. Adequate but with clear gaps.

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 ticker, metric (default revenue), and periods (default 3, max 5) are already documented in the schema. The description adds no syntax, valid metric keys, or period-format guidance beyond that baseline.

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 the resource precisely (metric broken down by business segment, product line, or geography) and names its data origin (latest 10-K XBRL instance). It also explicitly distinguishes itself from the companyfacts-based siblings by noting those carry no segment dimensions, so an agent can route correctly.

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 parenthetical that companyfacts carries no segment dimensions is an implicit routing rule: use this tool when segment/product/geography breakouts are needed, not get_company_facts. It stops short of an explicit 'use X when Y' statement, but the context is clear.

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