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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive, so the safety profile is covered. The description adds that it uses the Euclidean algorithm and returns {gcd, lcm}, which is modest but genuine added context for a pure computation.

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?

Front-loaded with the core action, then return shape, then a cross-reference. Compact and largely waste-free, with only the list_bundles pointer being of marginal value.

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 two-integer pure-computation tool with full schema coverage, annotations, and an output schema, the description supplies everything needed to call it correctly. Return format is even restated despite the output schema handling it.

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 both 'a' and 'b' documented as integers. The description only restates 'two integers', adding no syntax, range, or edge-case meaning beyond the schema. Baseline 3 is appropriate.

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 (Calculate) and precise resources (GCD/PGCD and LCM/PPCM of two integers), plus the algorithm used. This clearly distinguishes it from the hundreds of adjacent calculate_* siblings.

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 description implies its use case (compute GCD/LCM) but gives no explicit when-to-use or when-not guidance relative to alternatives. The pointer to list_bundles for related 'math' calculators is a discovery aid, not functional selection guidance.

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