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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered; the description adds the useful operational traits 'offline' and 'instant'. It does not disclose failure behavior (unknown nutrient synonyms, out-of-range ages, missing life-stage combos) or output units. There is also mild tension between 'offline' and openWorldHint=true, though 'offline' plausibly describes execution mode rather than data scope.

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 zero filler, front-loading what is returned before the operational note. Every clause carries 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 enumerates the return payload (RDA, EAR, AI, UL plus UL-protection rationale), which is the key gap-filler. It is nearly complete for a simple reference lookup; only error/edge-case behavior and output units are unaddressed.

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 75%, close to the high-coverage baseline where the schema does the heavy lifting. The description adds that the nutrient is 'one vitamin or mineral' and that values are keyed to age and sex, but it says nothing about the optional life_stage parameter or the age-fraction convention, so it only marginally extends the schema.

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: retrieves NIH reference values (RDA, EAR, AI, UL) for a single vitamin or mineral keyed by age and sex. It even names the returned data fields and the UL-protection context, so an agent knows exactly what this returns. No sibling tool overlaps with reference-value lookup, so differentiation is automatic.

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?

Usage is implied rather than stated: 'Offline and instant' hints this is the preferred local lookup over network calls, and the nutrient/age/sex framing implies the use case. But there is no explicit when-to-use, when-not, or named alternative, and no guidance on how to handle an unknown nutrient or an age/sex combination that has no value.

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