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

Annotations cover write/openWorld/non-idempotent/not-destructive, yet the description adds real behavioral value beyond them: the privacy consequence ('visible to all Mureka users'), the terminal endpoint (POST /files), and the downstream consumption path via ref_id into mureka_create_song_with_lyrics and mureka_create_instrumental.

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?

Dense but front-loaded: upload action first, constraints and cross-references after. The long parenthetical and chained clauses make it slightly crowded to scan, though nearly every clause carries usable information.

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?

With no output schema, the description compensates by naming the return values (ref_id and file url), and it covers visibility, source options, tag sourcing, and follow-up tools. An agent has everything needed to invoke this correctly and use the result.

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 the schema carries the baseline. The description still adds meaning the schema lacks: that title/mood/genre are mandatory, that valid mood/genre values should be sourced from mureka_list_styles, and that the audio gets trimmed to ~30 s. It says nothing about the optional youtube or account parameters, but those are self-documented.

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+resource ('Upload an MP3 as a reference track') and immediately scopes the accepted sources (public https url or base64). The 'reference track' framing distinguishes it from siblings like mureka_upload_motif, mureka_upload_vocal, and mureka_import_youtube.

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 concrete operating context (Mureka consumes ~30 s, so trim first; tags come from mureka_list_styles) and routes lifecycle actions to siblings (mureka_list_files for listing, mureka_delete_file for deletion). It does not, however, explain when to choose a reference track over mureka_upload_motif or mureka_upload_vocal, leaving that comparison to inference.

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