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

The description explains the analysis method (pitch class distribution, Pearson correlation, 15 scales) and discloses the full return structure including confidence rating. It adds substantial behavioral context beyond the readOnlyHint annotation, without contradicting it.

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 long but well-structured with clear sections: purpose, method, scale list, return fields, use-before list, parameter definitions, and a concrete example. Every section earns its place and the core statement is front-loaded.

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?

The description covers the tool's full behavior: what input it needs, what analysis it performs, what it returns, how it relates to other tools, and a usage example. Given the tool's analytical complexity and the sparse schema, this description is complete and leaves no essential gaps.

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 0%, but the description provides meaningful explanations for all three parameters: unit_index (AU index), track_index (Note track index), and region_index with special values (-1 = first region, -2 = all regions). This fully compensates for the schema's lack of 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 statement: 'Detect the musical scale/key from MIDI notes in a region.' It also explicitly distinguishes itself from the sibling tool detect_key, which works on WAV audio, making the tool's purpose and scope unmistakable.

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 directly contrasts with detect_key (audio vs MIDI) and provides an explicit 'Use this before' list naming force_scale_notes, diatonic_transpose_notes, generate_melody, and reharmonize_progression. This gives clear when-to-use guidance and alternatives.

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