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

Annotations already establish that this is a read-only, idempotent, non-destructive, closed-world operation. The description adds meaningful behavioral detail beyond that: it flags likely mg/mcg mix-ups against published ranges and returns a calculator link, which tells the agent what to expect from the response.

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 dense sentences front-load the core calculation scope, then follow with the range-check behavior and return value. Every sentence adds information; there is no filler.

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 an 8-parameter calculator with three modes and no output schema, the description covers the main input modes, the optional peptide behavior, and the returned link. It does not spell out the structure of the numeric results, but the essential invocation context is present.

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 baseline is 3, but the description adds mode-level semantics: dose versus unitsDrawn are alternative inputs, and supplying peptide adds an IU factor, a range check, and published injected ranges. This clarifies how parameters interact in ways the flat schema does not.

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 a specific resource (single-peptide vial reconstitution) and verb (exact math), and enumerates the three supported calculations: syringe units for a dose, concentration/doses per vial, and dose held in given units. 'Single-peptide vial' also implicitly distinguishes it from the peptide_blend_calculator sibling.

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?

Clear context is given: it is for single-peptide vial math, with the optional peptide parameter triggering range checks. It does not explicitly name alternatives like peptide_blend_calculator or peptide_supply_calculator, so the agent must infer that blends belong elsewhere, but the scope is otherwise clear.

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