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

With no annotations, the description carries the full burden of behavioral disclosure. It explains the internal arpeggiation behavior (cycling through chord tones, pattern types, bars_per_chord switching) and what is returned, but it does not mention side effects like whether existing notes on the target track are overwritten, added to, or whether a track/region must pre-exist. It also does not explain the meaning of start_beat or unit_index, leaving some behavioral ambiguity for a creation tool with no safety annotations.

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?

The description is longer than two sentences, but it is well-structured with clear sections for introduction, parameter meanings, returns, and examples. Each parameter gets its own line, and the examples are concrete and relevant. There is minor redundancy (e.g., 'synthwave/trance arp engine' followed by listing the same genres elsewhere), but overall it is efficient and front-loaded with the core purpose.

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 9-parameter tool with no annotations but an output schema, the description is quite thorough: it explains the core parameters, provides return value hints, and gives three usage examples. Gaps include no mention of start_beat and unit_index, no explicit side-effect/prerequisite discussion, and no detailed output-schema match. These are minor compared to the richness already provided, so it earns a solid 4.

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?

Despite 0% schema description coverage, the description compensates well for most of the 9 parameters. It details all five pattern values with note sequences and musical context, explains bars_per_chord, octave ranges, velocity range, step_duration durations, and typical track_index. However, it omits any explanation of start_beat and unit_index, which are less self-explanatory and appear in the schema without descriptions.

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 opens with a specific verb-resource pair: 'Create an arpeggiated chord progression' and repeatedly calls it an arpeggio engine. It explicitly distinguishes itself from the sibling create_arpeggio by stating 'Unlike create_arpeggio (which takes a single chord), this cycles through a full progression.' This clearly communicates the tool's scope and unique value.

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 explicitly tells when to use this tool versus create_arpeggio: 'Unlike create_arpeggio (which takes a single chord), this cycles through a full progression.' It also references the same progression format as create_chord_pads and gives genre-specific examples (synthwave, trance, house) with concrete parameter choices, which serve as usage patterns. This is explicit alternative and when-not guidance.

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