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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so safety is covered by structured data. The description adds real value beyond that: it discloses a per-call cost ('1 credit'), states the underlying computation method (deterministic GCD-based formula), and constrains inputs to positive integers. It doesn't say what happens on invalid input, but with annotations in place this is a solid addition.

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 with no wasted phrasing, and the cost note is a useful parenthetical. The mathematical formula is not strictly necessary for invoking the tool, which keeps it just short of ideal conciseness.

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 trivial two-argument pure-math tool with full schema coverage and annotations covering safety and idempotency, this is complete. The only conceivable gap is the return-value type, which is inferable from 'least common multiple' and unproblematic given the absence of an output schema.

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%, so both 'a' and 'b' are already documented as required positive integers. The description only restates 'two positive integers' and names them in the formula, adding no new meaning such as range limits or behavior for large values. Baseline 3 applies when the schema carries the 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?

The description names a specific verb ('Computes') and resource ('least common multiple (LCM)') with scope ('of two positive integers'). It is trivially distinguishable from the sibling greatest_common_divisor, and the stated GCD-based identity confirms exactly what is being computed.

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 explicit when-to-use or when-not-to-use guidance and no mention of the related greatest_common_divisor sibling. The 'two positive integers' phrasing implies an input constraint, but an agent gets no routing advice or edge-case handling guidance from the text.

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