update_song

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

Annotations already declare readOnlyHint=false, destructiveHint=false, and openWorldHint=false, so the mutation/safety profile is known. The description adds a genuinely useful behavioral fact beyond the annotations: changes apply live, including during playback. It does not say whether unspecified settings are preserved, whether changes are undoable, or what is returned, so it remains a modest addition rather than rich behavioral context.

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?

Two short sentences with no filler. The core purpose is front-loaded and the live-apply behavior follows immediately.

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 6-parameter tool with zero required parameters and full schema description coverage, the schema carries the parameter burden, and the description supplies the one non-obvious behavioral trait (immediate application during playback). No output schema exists, so return-value details are not required, though stating whether omitted settings stay unchanged would close the remaining gap.

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 100%, and each parameter has explicit bounds, defaults, and units (bpm default 120, swing -10 to 10, bar_size purely visual, etc.). The description adds no parameter-level meaning beyond the schema, so the baseline of 3 is appropriate.

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 gives a specific verb+resource: "Changes song settings." This clearly separates it from update_pattern and update_instrument implied by the resource, though it never names those siblings or enumerates the settings it can change. The schema carries the field list, so an agent can still identify the tool's purpose without opening anything else.

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?

There is no when-to-use guidance, no prerequisites, and no explicit alternative named among the many sibling tools (update_pattern, update_instrument, create_song, etc.). "Takes effect immediately, even during playback" describes effect timing, not when the agent should choose this tool over alternatives.

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