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

Annotations already declare readOnly, idempotent, non-destructive and open-world, and the description adds real context beyond them: only currently-running jobs, the maxJobs/429 relationship, and the underlying GET /jobs endpoint. It does not say whether the listing spans all accounts or is capped/paginated, so result-set behavior is only partly disclosed.

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?

The content is front-loaded with what is listed, then the exclusion/alternative, then the diagnostic use case. Every clause carries information; there is no filler or restatement of the title.

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 parameters, no output schema and safety already covered by annotations, the description supplies precisely what is missing: which jobs appear, which fields come back, and the practical reason to call it. Nothing an agent needs in order to call it correctly is absent.

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?

The tool takes zero parameters, so there is no parameter semantics to explain and the baseline is 4. The description correctly avoids inventing filtering options, consistent with the empty schema and additionalProperties: false.

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 resource and scope: 'The song and stem-split jobs running now', and names the returned fields (jobid, account, model, start time). The exclusion ('finished jobs are not listed') and the pointer to acemusic_get_job make it distinguishable from the sibling without opening either 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?

Explicit when-to-use: diagnosing why a submit returned 429 because each account runs up to its maxJobs. Also explicitly names the alternative for the excluded case ('finished jobs ... read them with acemusic_get_job'), which is exactly the when-not guidance an agent needs.

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