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

With no annotations, the description carries the full behavioral burden and does disclose a genuinely useful trait absent from structured data: the cost of 1 credit per call, plus the optional nature of transposition. It stops short of describing output shape or error behavior for invalid input, but the cost disclosure is real value.

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?

Two tightly written sentences: capabilities first, then the optional transpose modifier and cost note. Every clause earns its place and nothing is padded.

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 pure-computation tool with no output schema and no annotations, the description covers the three operating modes and cost adequately; the rule that return values need not be explained applies. The remaining gap is how progression and scale interact when both are supplied, which is not clarified.

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 50% (root and progression are described, scale and transpose_semitones are not). The description compensates by naming scales/modes, diatonic-chord construction, roman-numeral progression syntax with an example, and optional transposition, mapping the free-text capabilities onto the parameters.

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 states three concrete capabilities with specific verbs and resources: look up scale/mode notes, build diatonic chords of a key, and convert roman-numeral progressions to chords. This clearly separates it from siblings like midi_generate or tempo_calculator, so an agent can identify the tool's domain immediately.

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?

It lays out three use-cases that imply when the tool applies (scales, diatonic chords, roman-numeral progressions) and gives a concrete input example ('I V vi IV'), but never states when to prefer it over alternatives or what prerequisites/combinations are needed. Usage is inferred rather than explicitly directed.

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