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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds real value by disclosing what the payload contains (sequence, BPM, keys, lyrics, chord chart) and that the chord chart can optionally be transposed, which the annotations do not convey.

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 names the tool's output fields, with the API endpoint appended as a compact reference. No wasted words.

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 read-only list tool with no output schema, the description adequately previews the returned fields and the transposition capability. It omits pagination specifics, but those are fully covered in the schema, leaving only a minor 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 100%, so page, page_size, files, song_id and chord_chart_key are all documented in the schema. The description's mention of transposition echoes chord_chart_key but adds no syntax or format detail beyond the schema, so baseline 3 applies.

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 (List) and resource (arrangements of one song) and enumerates the returned content (sequence, BPM, keys, lyrics, chord chart). Clearly distinguishable from the sibling elvanto_list_songs, which lists songs rather than their arrangements.

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?

Implies the correct workflow by noting song_id comes from elvanto_list_songs, giving the agent context for when this tool applies. It does not state exclusions or explicitly contrast with alternatives, but for a narrow read tool the context is clear.

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