calculate_peg_ratio

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

With no annotations, the description clearly explains data sources, unit conversions (YOYNI ratio vs percent), and return values (peg=None under conditions), though could be more explicit about output structure.

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?

Well-structured with formula, explanation, and args section; no fluff, though slightly lengthy.

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?

Covers key aspects like undefined conditions and output fields (growth_period, growth_period_type) but lacks explicit return structure without an output schema.

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?

The single parameter 'code' is described only as 'Stock code' with no format details, adding minimal value beyond the schema's type and name.

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 the formula for PEG and specifies the inputs (PE_TTM, YoY growth), making the purpose clear and distinct from sibling tools like DCF or DDM valuation.

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?

Provides extensive conditions when PEG is undefined (PE==0, PE<0, no growth report, growth<=0) with reasoning, but does not explicitly compare to alternative valuation tools for when to use PEG vs others.

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