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

The annotations only declare readOnlyHint, while the description adds substantive behavioral context: row-to-fiscal-year mapping, null handling for withheld guidance, the 0–1 ratio scale, and ISO 8601 UTC date conventions. It does not describe response shape or error behavior, but it provides considerably more than the annotations alone.

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 and output semantics are front-loaded and organized clearly. The full Japanese translation repeats the English content and the date-format guidance is repeated, adding some redundancy, but the overall structure remains readable and purposeful.

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 the returned forecast metrics, row semantics, null handling, ratio scale, and date formats. It mentions forecastTarget without defining it and does not describe the overall response structure, but the definition is broadly sufficient for correct use.

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 baseline is 3. The description adds meaning beyond the schema by explaining that FY rows carry next fiscal year guidance while Q1–Q3 rows carry current fiscal year guidance, which clarifies the period filter’s effect; it adds little for limit or symbol beyond what the schema already says.

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 that this tool returns company guidance from each earnings release, with specific metrics such as revenue, operating income, net income, EPS, and derived ratios. The forecast/guidance framing distinguishes it from actual financial statement siblings, but it does not explicitly name an alternative tool, so it falls short of the strongest sibling differentiation.

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 explains how FY versus Q1–Q3 rows should be interpreted and that withheld guidance is null, which gives meaningful usage context. However, it does not say when to choose this tool over get_income_statement, get_key_metrics, or other financial siblings, and it gives no explicit exclusions.

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