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

Annotations already declare readOnly/openWorld/non-destructive, but the description adds real context beyond them: the free-vs-premium day-range limit, the caveat that totals can be underestimated with incomplete manufacturer data, and the required Cotlet API key. These are genuine operational caveats an agent cannot infer from structured fields.

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 what it returns, then constraints and caveats in descending priority. Slightly long at five sentences, but each sentence (return shape, view parity, tier limits, data caveat, auth) carries distinct information.

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 correctly carries the return contract — totals, averages, and goal gap — plus tier limits and the auth requirement. An agent has enough to invoke and set expectations without further fields.

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% with both date parameters documented as YYYY-MM-DD, so the schema carries the parameter detail. The description reaffirms date-range semantics but adds no format or validation nuance beyond it — baseline 3 is appropriate.

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+resource (get nutrition summary) and enumerates exactly what it returns — total and average calories/protein/fat/carbs plus gap to goal. It distinguishes itself from sibling reads like fitatu_get_diary and fitatu_get_daily_goals by being an aggregate over a range.

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?

It gives useful context — 'Returns the same balance the Summary view shows' — and names plan-based limits (free 1–7 days, Premium any period), which helps a caller decide if the range is valid. However, it never states when to prefer this over fitatu_get_diary or fitatu_get_daily_goals, leaving alternative selection implicit.

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