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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, closed-world). The description adds output content that is not in any schema: it returns selling price, profit per unit, and the true gross margin. With no output schema present, this disclosure is genuinely useful rather than redundant.

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?

Three sentences with the concrete example front-loaded and the purpose statement second; every line earns its place. The trailing web page URL is the only filler, but it is brief.

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 simple three-parameter calculator with no output schema, the description covers inputs, the computed outputs, and the conceptual distinction between markup and margin. It is complete enough to call correctly; only cross-tool routing is absent.

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 three parameters are already documented with defaults and ranges. The description reinforces that markup is applied to cost, but adds nothing about currency behavior or how the markup value should be interpreted beyond what the schema already gives. Baseline 3 applies.

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 a specific verb and resource: set a markup on cost to see selling price, profit per unit, and gross margin. The lead example clarifies the markup-vs-margin concept crisply. It does not explicitly name the closely related sibling profit_margin_calculator, so the differentiation is implicit rather than stated.

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 explicit when-to-use, when-not-to-use, or named alternative, even though profit_margin_calculator sits right next to it in the sibling list. The example implies the scenario but an agent gets no routing guidance between markup and margin tools.

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