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

Annotations already declare readOnlyHint=true and idempotentHint=true, so the safety profile is covered and the bar for the description is lower. The description adds the useful computation semantics (gross profit, margin, markup outputs, target-margin sizing), but says nothing about precision, rounding, error behavior, or result format, which matters with no output schema.

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, front-loaded with a concrete example that teaches the margin-vs-markup distinction the tool is built around, followed by the input/output summary and the source URL. The opening example is partially illustrative rather than strictly instructional, but it earns its place by disambiguating the core concept.

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 usefully names the return values (gross profit, margin, markup). However, it promises capability ('prices for target margins') that has no corresponding parameter in the schema, which leaves the agent unsure whether an alternate input mode exists or how to invoke it.

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 cost, revenue and currency are already documented in the schema, establishing a baseline of 3. The description only restates that cost and revenue are entered and omits currency entirely; it adds no syntax, unit, or constraint detail 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 names the resource (profit margin) and enumerates the outputs produced from cost and revenue: gross profit, margin and markup. It is clear about what the tool computes, but it never distinguishes itself from the sibling markup_calculator, which is a real ambiguity risk since markup is explicitly mentioned here.

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?

Usage is only implied: 'Enter cost and revenue...' tells the agent what inputs map to what outputs, which implicitly signals the scenario to use it in. There is no explicit when-to-use statement and no routing to alternatives like markup_calculator or break_even_calculator, so the agent must infer.

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