get_ratio_history

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

With no annotations, the description must carry the burden of behavioral disclosure. It reveals accepted ticker formats (CIK, stripped CIK, historical ticker resolution) and enumerates valid ratios, which is helpful. However, it omits behavior around invalid inputs, data coverage, or return structure beyond stating 'time series'.

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 description is a single focused sentence followed by a list of valid ratios and a brief argument note for ticker. It is efficient and front-loaded, though the ratio list could be more compact as a bulleted list.

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?

Despite having an output schema, the description leaves significant gaps: it does not explain the 'period' parameter (annual default) or year-range parameters, nor does it clarify how the time series is keyed or what data span is available. Given 5 parameters and only 1 fully explained, the description is incomplete for an agent to invoke the tool with confidence.

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 0%, so the description must compensate. It only explains the 'ticker' parameter in detail. The 'ratio' parameter is implicitly constrained by the valid ratio list, but 'period', 'to_year', and 'from_year' are completely unmentioned, leaving their meaning and defaults ambiguous.

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 clearly states 'Get a single financial ratio over time' with a specific verb, resource, and scope. It distinguishes itself from sibling tools like get_ratios by emphasizing 'single' and 'over time' (time series), and provides an explicit list of valid ratios.

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 implies usage for trend analysis ('Returns a time series for trend analysis') but does not explicitly state when to prefer this over alternatives like get_ratios or get_financial_metric. No exclusions or alternative tool names are mentioned.

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