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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds genuinely useful behavioral context beyond that: the exact half-up rounding policy (as opposed to banker's rounding) and that output includes both plain and scientific notation.

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?

A single dense sentence that front-loads the operation, then the rounding policy, then the return format. Every clause carries information and there is no filler.

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?

For a pure, idempotent, read-only numeric transform with a full schema, an output schema, and complete annotations, the description supplies everything an agent needs to invoke it correctly. Error handling and pagination are irrelevant here.

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 100%, with the value format (signed decimal string, optional exponent, no commas) and the significantFigures bounds fully documented in the schema. The description's phrase 'a chosen number of significant figures' merely echoes the parameter name, so it adds no meaning beyond structured fields — baseline 3 applies.

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?

The description names a specific verb (round), resource (decimal string), and the precise operation (to a chosen number of significant figures), which is enough to separate it from siblings like round_decimal or decimal_to_fraction on semantics alone. However, it never explicitly names the neighbouring rounding tool it could be confused with, 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?

There is no when-to-use or when-not-to-use guidance and no alternative tool is named, even though round_decimal and scientific_notation sit right beside it. The description only states what the tool does, leaving the agent to guess which rounding sibling fits a given request.

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