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

Annotations already declare readOnlyHint and idempotentHint. The description adds transparency by noting it returns both ABC and Strudel forms and explains task-specific input requirements (e.g., 'detect-chord/detect-key need notes or chords'). This meaningfully extends beyond the annotations without contradiction.

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 efficiently structured as a single paragraph that lists tasks and required inputs without redundancy. It avoids repeating schema details while providing necessary context, though it is a bit dense.

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?

Given the absence of an output schema, the description clarifies the return formats (ABC chord-symbol spelling and Strudel form). It also explains parameter dependencies for each task, making the tool self-contained and usable without external references.

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?

The schema covers all 5 parameters with descriptions (100% coverage). The description adds valuable task-to-parameter mapping (e.g., 'suggest-progression/key-chords need a key'), which gives extra semantic clarity beyond the schema alone.

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 clearly states the tool's purpose with specific verbs: 'name a chord', 'guess the key', 'get a progression', 'list what fits a key'. It distinguishes itself from sibling tools (conversion, guides, playing, searching) by focusing on harmony analysis, making its role obvious.

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 provides explicit usage guidance: 'Use it before writing chord symbols for a style preset, or to check a harmonization.' While it doesn't explicitly mention alternatives or when not to use it, the guidance is direct and actionable.

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