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

No annotations are provided, so the description carries full burden, and it excels: it explains that a new region is created, the original is trimmed, and that straddling notes are kept in the original region (with a DAW-behavior rationale). It also states that the function returns original and new region details, covering key behavioral expectations.

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 well-structured and front-loaded, starting with a clear one-sentence summary followed by behavioral details, use cases, parameter explanations, and an example. Every section earns its place and the example illustrates usage concretely without redundancy.

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 tool has moderate complexity with four required parameters and an output schema, and the description provides comprehensive coverage: behavior, parameter constraints, edge-case handling, return value note, and an example. The output schema covers return structure, so the description needn't detail that further.

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%, and the description fully compensates by explaining each parameter: unit_index is 'AU index', track_index is 'Note track index', region_index is 'Region to split (0-based)', and split_beat is 'Absolute beat position to split at (must be within region range)'. This adds significant meaning beyond the bare parameter names.

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 'Split a note region into two at a given beat position,' a specific verb+resource+parameter statement that clearly defines the operation. It distinguishes this from sibling tools like delete_note_region, duplicate_note_region, and merge_note_regions by explicitly describing the split behavior.

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 'Use cases' section provides clear contextual guidance, including dividing long regions, cutting silence off the end, creating variations, and preparing for arrangement edits. It doesn't explicitly name alternatives or say when not to use it, but the listed scenarios make the appropriate usage clear.

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