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

Annotations already declare readOnlyHint=false, destructiveHint=true, and openWorldHint=false, so the safety profile is covered. The description adds non-obvious context beyond that: the credit cost (2), that the original is preserved, and that MCP Apps hosts render a progress card then play the result. The preservation wording sits in mild tension with destructiveHint=true, but spending credits reasonably explains that flag.

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?

Front-loads the core action, then layers cost, the style-agreement prerequisite, and the host UI behavior. Every sentence carries information and nothing is padded, though the multi-clause opening is slightly 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?

An output schema exists, so return values need not be explained. The description covers the cost, the preservation guarantee, and the progress/playback UX, which is enough for an agent to invoke it correctly; only the sibling disambiguation is missing.

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%, so all four parameters (style, title, lyrics, songId) are already documented in the schema. The description restates the style dimensions and the 'own words unless new ones are given' default, adding little beyond the schema. Baseline 3 applies when the schema does the heavy lifting.

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?

States a concrete verb and resource ('Make one of their songs again in a new style') and specifies the dimensions being transformed (genre, mood, instruments, voice). It hints at differentiation from change_lyrics via 'with its own words unless new ones are given' and 'keeps the original', but never names the close sibling generate_remix, leaving that distinction to inference.

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?

'agree the style with them first' gives a real prerequisite, and the 2-credit cost is disclosed, which is useful for deciding whether to call it. However, there is no explicit when-to-use-vs-alternative guidance against generate_remix, generate_song, or change_lyrics, so the agent must infer which tool applies.

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