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

Annotations already declare readOnlyHint=true, idempotentHint=true and openWorldHint=false, so the safety profile is covered. The description adds genuine output context with no output schema present ('see the working and the simple average'), but it stays vague about what 'the working' contains and says nothing about how missing or zero weights are handled.

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?

Three sentences, no padding, and the illustrative example lands in the first sentence. Front-loading a worked example instead of a plain purpose statement is slightly suboptimal, and the trailing URL adds little for an agent.

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 simple, all-optional numeric tool with no output schema, the description covers inputs, pairing, weight units, and the shape of the result, and the annotations carry the safety profile. Only the treatment of omitted values/weights and the output format remain unspecified.

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%, so the baseline is 3, but the description adds real meaning beyond the schema: it establishes that values pair positionally with weights, that up to six pairs are accepted, and that weights are expressed as percentages (30%, 20%, 50%) rather than fractions.

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 identifies a weighted-average calculation with concrete inputs (up to six values with weights) and contrasts it implicitly with a simple average ('82.5, not 84.3'). It is distinguishable from the nearby average_calculator, though it never names or explicitly rules out that sibling.

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?

The scoring example implies the use case (weighted grades/scores), but there is no explicit when-to-use or when-not statement, and no sibling is named as an alternative even though average_calculator, grade_calculator and gpa_calculator are close neighbors. Usage is only implied.

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