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

Annotations already declare readOnlyHint=true, destructiveHint=false and idempotentHint=true, so the safety profile is covered. The description adds genuinely new context: 'Nothing is created or charged by this tool' and the destination 'needs a free account,' which matters for an agent setting user expectations. It stops short of describing the returned link's lifecycle or expiry.

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?

Three sentences, each earning its place: what it does, when to use it, and the crucial no-cost/external-account caveat. The key distinction (it prepares a link, it doesn't make the song) is front-loaded rather than buried.

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 the link's exact shape need not be re-explained, and annotations cover the safety profile. The description closes the remaining gaps an agent would care about — no charge, external site, free account required. Only the fate of the generated link (persistence, expiry) is left unstated.

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 both 'idea' and 'language' are already documented in the schema, and the enum of 24 languages is fully enumerated there. The description only alludes to the idea parameter via 'the user's song idea already filled in' and says nothing about language handling. Baseline 3 is appropriate when the schema carries the load.

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 specific verb and resource: it 'prepares a link that opens the SongUp AI song maker on songupai.com with the user's song idea already filled in.' The purpose is unambiguous and clearly a creation-path tool rather than a lookup. It does not explicitly name the siblings (find_songs, find_audio_tool) to differentiate itself, so it lands short of a 5.

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?

'Use it when the user wants a song made from their own idea, story, names or lyrics (birthday, anniversary, love song, etc.)' gives concrete trigger conditions with examples. It lacks an explicit exclusion or a named alternative for cases like finding an existing song, so the guidance is clear but not fully routing.

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