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

Annotations already cover the read-only/idempotent/non-destructive profile, so the description adds genuine behavioral context on top: it counts whole doses (a rounding rule) and caps usable doses by the mixed-vial shelf life taken from the dataset. It stops short of stating edge-case behavior (e.g., what happens when a vial cannot cover a single dose).

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 tight sentences, front-loaded with the purpose and then the behavioral caveats. No filler and nothing repeated from the title or schema.

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 enumerates what comes back (duration, vial count, three cost figures), which is the key thing an agent needs. It omits return units/currency conventions and how whole-dose rounding affects the cost figures, which would matter for interpreting results.

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 100%, so the schema already documents all nine parameters, including the useWithinDays override. The description reinforces the conditional link between peptide and shelf life/IU factor but adds no format or unit detail beyond the schema, so the 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?

States a specific verb (plans) plus the exact outputs: vial duration, vials per cycle, and cost per dose/week/cycle. That output list implicitly separates it from peptide_reconstitution_calculator and peptide_blend_calculator, but no sibling is named explicitly.

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?

Conditional guidance exists ('when pricePerVial is given' for cost answers, 'from the dataset when a peptide is named'), but there is no statement of when to choose this tool over the reconstitution or blend calculators. Usage must be inferred from the described outputs.

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