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

Goes well beyond the readOnlyHint annotation by disclosing that the underlying vendor response is unpaginated and that results are capped at 5000 rows / 2MiB here — a truncation risk the agent must know about. It also clarifies that duration days are inclusive and interpreted in company timezone, which affects how returned values should be read.

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?

Four short, front-loaded clauses with no filler: scope, semantics, endpoint, and result limits. Slightly hurt by compressed formatting ('to5000rows and2MiB') that reads as a token artifact rather than deliberate style.

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 does the necessary work: it names what is returned (supplement definitions), how durations are counted, and the size bound on the result set. It does not enumerate returned fields, but for a simple zero-param read the agent has enough to call it and interpret truncation.

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?

The tool takes no parameters, so the schema carries nothing to elaborate on; baseline is 4. The description correctly spends no words on inputs and instead uses the space for return-value semantics.

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 ('Read supplement definitions') and adds a scope boundary by excluding flex-hour supplements, which is a related-but-distinct concept an agent could confuse it with. It does not name a sibling tool to route to, so it stops short of full sibling differentiation.

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?

'not flex-hour supplements' is an explicit exclusion that tells the agent when this tool is the wrong choice. There is no positive when-to-use condition or named alternative, but for a zero-parameter list endpoint the exclusion carries most of the routing value.

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