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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds valuable context: 'Pure-math + lookup, no engine call, fully deterministic' and includes an anti-fabrication instruction with exact closed-form formulas, going beyond the annotations to clarify deterministic behavior and prevent hallucination.

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 dense but no more than needed: four sentences pack purpose, output elements, usage trigger, and anti-fabrication guidance. It is front-loaded with the core action and avoids redundant phrasing.

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?

With no output schema, the description fully enumerates what the tool returns (regime, action, MTTF, B-life) and even provides the exact formulas for MTTF and B-life. Combined with rich parameter descriptions and clear annotations, the description gives an agent everything needed to invoke the tool correctly and interpret its result.

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%; both beta and eta have detailed descriptions already. The tool description adds interpretive context for beta (bathtub regimes) and ties eta to MTTF/B-life outputs, but these are are return semantics rather than parameter syntax or format details. Baseline 3 is appropriate given the schema covers the mechanics.

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 opens with a specific verb+resource: 'Given a Weibull shape parameter β ... return a plain-language interpretation' and enumerates the exact outputs (bathtub-curve regime, suggested action, MTTF/B-life). It clearly differentiates from siblings by focusing on interpreting β into actionable guidance, and explicitly states it is a pure-math lookup with no engine call.

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 provides an explicit usage trigger: 'Use when a user reports a fitted β and wants to know what to DO with it.' It establishes clear context but does not name alternative tools or state when not to use it, so it stops short of a full when/when-not/alternatives treatment.

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