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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, and the description adds meaningful extra context: pure arithmetic with no I/O or external calls, rounding to 2 decimals, that only method is required, that other-method parameters are accepted and ignored, and that unknown methods or missing required parameters return errors. This is rich behavioral disclosure beyond the annotations, though it could say more about output shape (which the output schema covers).

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?

It is long but dense and front-loaded with purpose and the key alternative, and the per-method parameter list earns its place given the 23-parameter, method-dependent design. A reader gets routing guidance and requirements without wasted sentences, though the length is at the upper end.

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?

Given an output schema that covers return values and annotations that cover the safety profile, the description supplies the remaining essentials: method selection, per-method inputs, unit conventions, defaults, and error behavior. Nothing an agent needs to call it correctly is missing.

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, but the description adds conditional method-to-parameter mapping (e.g. wacc needs equity_value + debt_value; dlom_finnerty volatility is annualized) that JSON Schema cannot express on its own. It also clarifies decimal conventions and default handling, giving it value above the schema alone.

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 ('Construct discount and capitalization rates') and enumerates the supported methods, so the agent knows exactly what the tool computes. It also names the sibling valuation_time_value as the tool for the cash flows this rate discounts, distinguishing it from alternatives.

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?

Explicitly says when to use it ('derive the rate that feeds every income-based method') and routes cross-border cases to method currency_adjusted, while pointing to valuation_time_value for the discounted cash flows. Both the use condition and the alternative are named.

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