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

Annotations already declare readOnlyHint=true, so the safe-read profile is covered. The description adds genuine behavioral context beyond that: the ranked best-first ordering, the parallax/reading-error risk dimension, and the 'Research use only' scope limitation. It does not contradict the annotation.

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 with the comparison scope, the output dimensions and the sorting rule front-loaded, plus the safety disclaimer at the end. No filler or repetition.

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 (units, fit, relative error, ranked order) and flags research-only use. But for a 5-parameter tool at 0% schema coverage, the inputs most needed to call it correctly (peptide, vial_mg, water_ml, lang) remain undocumented.

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% across 5 parameters, so the description carries the full burden and largely fails: only 'target dose' loosely maps to dose_mcg, while vial_mg, water_ml, peptide and the lang enum are unexplained. An agent must infer the reconstitution inputs entirely from parameter names.

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 and resource (compare U-100 vs U-40 syringes for one target dose) and even enumerates the comparison outputs (units required, fit, relative reading error). This clearly separates it from siblings like calc_reconstitution or plan_schedule without opening their schemas.

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?

'for one target dose' implies the context (a single dose you want to read accurately), and 'Sorted best-first' implies the decision it supports. However, there is no explicit when-to-use/when-not statement and no alternative tool named for related tasks such as reconstitution volume calculation.

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