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

With no annotations, the description carries the full burden, and it does disclose the return unit ('as a percentage'), which is genuinely useful. It does not state how taxRate is applied (tax shield), whether inputs are percentages or decimals, or any validation behavior, leaving meaningful ambiguity for a formula tool.

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?

Two short sentences, with the identity of the calculation front-loaded and the inputs following. No wasted words, though the value would be improved by trading some terseness for unit detail.

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 five-parameter calculation with no output schema and no annotations, the description covers purpose and output unit but leaves input conventions and formula semantics unspecified. Adequate to invoke, not sufficient to invoke correctly on the first try in ambiguous cases.

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 nominally 100%, but the schema's own descriptions are boilerplate ('Debt to process'), so the description's parameter naming and the 'optional taxRate' marker add real value. It still omits the crucial unit convention for costEquity/costDebt (percent vs. fraction), and its 'provide' phrasing implies four required inputs where the schema marks none required.

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 named financial formula ('Calculate Weighted Average Cost of Capital') plus the output form ('as a percentage'), so the agent knows exactly what computation this performs. It does not, however, contrast itself with any sibling calculator, so it stops short of a 5.

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?

There is no when-to-use guidance, no prerequisites, and no named alternative among the many sibling finance tools. The clause 'Provide equity, debt, ...' is an input enumeration, not usage direction.

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