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

Annotations already declare readOnlyHint=true, so the description doesn't need to restate that. However, it adds valuable behavioral context: explains how xr enables asymmetric fault criterion, how Ith/Idyn relate to thermal/dynamic withstand, and that Rct_ohm can be estimated. This goes beyond annotations, providing operational transparency.

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 paragraph that front-loads the main purpose. It includes parameter explanations and usage notes without excessive verbiage. While it could be more structured with bullet points, every sentence contributes value.

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 the tool's complexity (15 parameters, no output schema, no parameter descriptions), the description is remarkably complete. It covers the core algorithm, relevant standards (IEC 61869-2, NBR 6856, IEEE C37.110), and explains how each parameter affects the result. The lack of output schema is compensated by implying the result (smallest commercial primary).

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?

Despite 0% schema description coverage, the description explains many key parameters: burden (burden_VA, relay_ohm, cable_ohm), ALF, Icc_A, xr, I_load_A+Fter for thermal criterion, Ith/Idyn for thermal/dynamic, and Rct_ohm. It connects parameters to the mathematical criteria, adding meaning beyond the schema.

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 the tool's purpose: 'Dimensiona o TC de proteção (IEC 61869-2 / NBR 6856): menor primário comercial que NÃO satura na falta...' It uses a specific verb (dimensionar) and resource (TC de proteção) with detailed scope, and distinguishes itself from sibling tools by focusing on CT dimensioning, which no other sibling does.

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 does not provide any explicit guidance on when to use this tool versus alternatives. It mentions 'Gratuito (uso limitado)' but that's a limitation, not usage context. No comparisons to sibling tools or exclusion criteria are given.

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