get_shares

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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds genuinely useful behavior beyond them: the default 18-month coverage window, the truncation rule ('only the most recent limit points are returned'), and how to widen the window. It does not mention update cadence, auth, or whether values can be null.

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?

Three short sentences, front-loaded with the purpose, then result shape, then the windowing caveat. Nothing is filler and the most important constraint (18-month default) is placed where it will be read.

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?

An output schema exists, so return-value documentation is unnecessary, and annotations cover the safety profile. The description closes the main gap an agent would hit (date-window defaults and truncation). Minor omissions remain, such as units/currency-agnostic nature of the count and staleness of the series.

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 schema already documents all four parameters, including the 18-month default and the YYYY-MM-DD format. The description restates the start/limit behavior rather than adding syntax, ordering, or edge-case detail, 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?

States a specific verb and resource ('Get the shares-outstanding history for a Yahoo symbol') and describes the shape of the result (date + reported shares outstanding). No sibling tool covers shares-outstanding history, so an agent can distinguish it from get_holders, get_financials or get_company_info without opening a 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?

The description implies the use case (retrieving historical shares-outstanding series) and gives one actionable condition ('pass a start for anything older' than 18 months). It never names an alternative tool or states when a different sibling should be chosen instead, so guidance stays implicit.

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