transport

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

Annotations declare readOnlyHint=false, idempotentHint=false, destructiveHint=false, so the mutation/safe profile is already covered. The description adds genuine behavioral context beyond that: toggle_cue's playing-vs-stopped semantics and the arrangement-insert-marker detail ('which only the user controls'), plus capture_midi keeping recent MIDI. It also discloses the return value ('resulting transport state').

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?

It is front-loaded and dense, but the action enumeration substantially restates the enum values already present in the schema, which costs space. The routing sentences and per-action hints do earn their place, so it is functional rather than wasteful.

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 mutation tool with no output schema, the description covers the full action surface, the return value ('resulting transport state'), the one non-obvious parameter's semantics, and sibling alternatives. Remaining gaps (permissions, side effects of stop_all_clips) are minor against the annotation coverage.

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 coverage is 100%, so the baseline is 3, and the description earns extra by clarifying that jump_by 'needs `amount`: beats, negative jumps back' – the negative-direction semantics are not in the schema's terse 'Beats to jump (jump_by only)' text. This is meaningful added meaning over the structured field.

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 ('Transport and playhead actions') and enumerates the exact operations supported. It distinguishes itself from a few siblings by routing tempo/loop to set_properties and undo/redo to history, but the enumeration largely mirrors the enum rather than adding distinct framing.

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?

Explicit alternative routing is given: 'To change tempo or loop settings use set_properties on \'song\'. For undo/redo use the history tool.' This is clear when-to-use-elsewhere guidance. It stops short of when-not to use transport itself, but the alternatives are named concretely.

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