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

Annotations only cover safety/idempotency, but the description adds billing cost (Mureka Gold), the mutual-exclusivity constraint on inputs, and the asynchronous result contract ('songs with song_id and mp3, or a jobid for mureka_get_job'). It even exposes the underlying endpoint. That is materially more than the annotations provide.

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-loaded with purpose and routing, then cost, then return shape, then endpoint. Mostly tight, but the fragment 'A job like mureka_create_song: songs with song_id and mp3, or a jobid for mureka_get_job' is telegraphic and slightly harder to parse than it needs to be.

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?

There is no output schema, so the description carries the return-value burden and does so by explaining the song_id/mp3 vs jobid outcomes. Combined with billing and the sibling routing, an agent has everything needed to call this correctly.

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; the description goes beyond it by stating that prompt and ref_id are mutually exclusive and by naming the tools that produce a valid ref_id (mureka_list_references, mureka_upload_reference). It does not add meaning for model/title/account, hence not a 5.

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 ('Generate two instrumentals (no vocals)') plus both input modes (prompt or reference track), and explicitly names the siblings it is NOT for (mureka_create_song, mureka_create_song_with_lyrics). An agent can distinguish it from every other generation tool without opening a schema.

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?

Gives explicit routing rules: prompt or ref_id 'not both', and 'For songs with vocals use mureka_create_song or mureka_create_song_with_lyrics'. It also discloses the cost gate ('Costs Mureka Gold'), which is a real precondition for choosing 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.