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

Annotations already declare read-only, idempotent, closed-world behavior, so the description only needs to add domain context. It does: it warns that the three bodies' scopes differ and that their numbers must not be merged, and it flags the output as reference rather than personal advice — a genuinely useful caveat absent from the 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?

Labeled fragments (Purpose/Guidelines/Limits/Ex) front-load the scope and constraints with no filler. The inline example earns its place by demonstrating invocation, though it repeats information the schema already implies.

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 return formatting need not be explained, and all three optional parameters are documented in the schema. The description supplies the domain caveats an agent needs (source scope, no cross-body merging, non-personal advice) but omits any note about result volume or whether coverage is exhaustive across the three bodies.

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 100% with enums and defaults documented, so the baseline is 3. The description adds a worked example showing a Chinese-language keyword, which confirms bilingual keyword input in practice and slightly exceeds the schema's terse '中英均可'.

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 resource (dietary guideline entries) and confines scope to three named bodies (WHO, China, US), which is enough to separate it from query_dietary_limits and the broader query_* tools. It stops short of naming that sibling explicitly, so the differentiation is inferential rather than stated.

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 when a question asks what a guideline body recommends' gives a clear triggering condition, and the Limits line adds an exclusion (reference only, not individual advice). It never names the nearest alternative (query_dietary_limits) or says when that one is preferred, so routing still requires inference.

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