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

Annotations already declare a safe, read-only, idempotent, closed-world computation, so the safety profile is fully covered elsewhere. The description adds only the dual computation modes and says nothing about edge cases (unreachable targets, weight totals not summing to 100, or exceeding max scores), which is mild added value over the annotations.

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 front-loaded sentence that leads with the primary computation and appends the optional mode. No preamble, no filler, 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 an output schema present the description need not explain return values, and annotations cover the safety profile, so the remaining burden is modest. It covers both computation modes adequately but does not clarify the schema's anyOf pairing constraint (target + finalWeight together) or behavior when the target is unreachable, leaving a small gap.

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 67%, above nothing but well below the 80% threshold where the schema would clearly carry the load. The description restates the meaning of 'target', 'finalWeight', and weighted categories at a high level but adds no format, unit, or constraint detail (e.g., the anyOf rule that target and finalWeight must be supplied together) beyond 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?

The description names a specific operation (weighted category average) plus an optional secondary output (final-exam percentage needed to hit a target), which uniquely separates it from generic calculators like average_calculator or percentage_calculator. It never names a sibling explicitly, so it stops short of a 5.

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 word 'optionally' signals that the final-exam calculation is conditional, giving implied usage guidance for the two modes. However there is no explicit when-to-use, when-not-to-use, or pointer to the closest alternatives (gpa_calculator, average_calculator) for the agent to choose between.

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