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

The annotations already declare readOnlyHint=true, non-destructive and closed-world, so the safety profile is covered. The description usefully adds the direction of the result ('steps upward'), which is behavioral detail beyond the annotations, but it says nothing about the result when the target is below the source key or the output format. Adequate but with a clear gap.

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 zero filler. Everything stated earns its place and the action is clear from the first clause.

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 no output schema, the description does state the reported value (semitone steps), which is what an agent most needs for this simple two-parameter calculator. The only gap is the ambiguity about downward transposition and whether the result is always a positive step count.

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 enums on both parameters, and the schema already documents fromKey and toKey, so the schema carries the parameter burden. The description adds no extra meaning about the two keys beyond the schema, which matches the baseline 3 for high coverage.

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 gives a specific verb and resource ('Transpose a musical key') plus the output ('number of semitone steps upward'), so an agent knows exactly what computation happens. The sibling tools are all unrelated finance/health/math calculators, so no sibling differentiation is needed, but the phrase slightly conflates transposition with interval measurement.

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 guidance on when to use this tool, no prerequisites, and no alternatives named. Usage can only be inferred from the tool name and description; nothing states when-not-to-use or how it relates to any other key/music utility.

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