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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered externally. The description adds return content (total mg, % of limit, time-of-day distribution), but the time-of-day claim is unsupported by any time input in the schema, which undercuts its reliability. No auth, rate-limit or persistence notes.

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?

The first two sentences are front-loaded and efficient, but the final sentence about list_bundles/'cuisine' calculators does not earn its place and distracts from a four-sentence description. Overall length is reasonable but not tight.

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?

An output schema exists, so the description's recap of return values is redundant yet harmless; the substantive gap is parameter semantics (units, enum meaning). For a one-param tool with zero schema coverage, that omission leaves the agent guessing how to express quantity, and the unsupported time-of-day claim is misleading.

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 0%, so the description must carry the parameter burden. It names the shape ('list of drinks (type, quantity)') but never specifies what a unit of quantity means (cups? ml? mg?) nor explains the coffee/espresso/tea/cola/energy_drink enum values or why quantity must be > 0 — the single most important ambiguity for a caffeine calculator is left open.

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 ('Track caffeine intake against the safe daily limit (400 mg adult)') and gives concrete scope (coffee/tea/soda consumption, list of drinks). It is distinguishable from similarly-named siblings like calculate_caffeine_clearance and calculate_caffeine_half_life by name alone, but the description never explicitly contrasts itself with them.

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?

'Use for monitoring coffee/tea/soda consumption' gives implied context but no when-not conditions and no routing to the three caffeine-related siblings. The closing pointer to list_bundles for 'cuisine' calculators is off-topic for a caffeine tool and adds noise rather than guidance.

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