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

Annotations already declare readOnly/idempotent/non-destructive, and the description reinforces rather than contradicts them by stating nothing is bought or saved. It adds real behavioral detail beyond the annotations: automatic conversion only for grams/milligrams/micrograms (IU and other units do not convert), flagging of amounts outside a daily serving, items that could not be included and why, and the fact that price is pre-shipping and pre-tax.

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?

Front-loaded with purpose, then rules in a logical order: input format, unit conversion, non-effects, outputs, eligibility. It is dense but mostly earns its sentences; the enumerated return contents partially duplicate the opening 'link to review and buy' phrase and the existing output 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?

Covers the hard parts an agent could get wrong — unit conversion limits, no-save semantics, age and geography restrictions — and an output schema already exists so the return-value list is supporting detail. The one material omission is any mention of the form parameter that controls capsule vs powder output.

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?

With schema description coverage at 0% for the top-level parameters, the description compensates well for items by explaining that each entry is the person's own naming, its amount/unit, and the ingredient_id from search. However, the form parameter (capsules vs powder) is never mentioned anywhere in the description or the schema, leaving a real semantic gap.

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?

Opens with a concrete verb and output: turn a list of supplements into one custom supplement plus a review/purchase link on picardo.health. It also names its sibling search_supplement_ingredients as the source of ingredient_id, so an agent can separate the two tools without opening either schema.

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?

Gives explicit preconditions and an explicit exclusion: purchases are for adults 18+ shipped in the US, and if the person is under 18 or outside the US the tool must not be called, with instructions on what to say instead. It also directs the agent to search_supplement_ingredients for the ingredient_id before calling.

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