Individual plays

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

Annotations already declare readOnly, idempotent, and closed-world, so safety is covered. The description adds real behavioral context beyond them: newest-first ordering, local-time values, the next_before pagination contract, and a cost signal relative to aggregate siblings. It stops short of stating default page size or limits (left to schema).

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 tight sentences, front-loaded with what is returned, then windowing, then pagination, then routing to cheaper alternatives. Every clause carries information; no filler.

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?

No output schema exists, so the description earns its place by describing the record contents and the next_before return value needed for paging. Combined with full schema coverage for the three parameters, an agent has everything required to call and iterate this tool 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, but the description adds meaning beyond the schema by explaining the window semantics of after/before together and tying next_before to the before parameter for paging. It does not restate formats already documented in the schema, which is the right split.

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 ('Individual stored plays') plus ordering ('newest first') and returned fields (local time, track, artists, album). It also names the sibling tools that cover the cheaper aggregate case, so an agent can place it against daily_play_counts and top_artists immediately.

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-not guidance: 'For counts over a range prefer daily_play_counts or top_artists, which are far cheaper.' It also gives the windowing recipe (after/before) and the pagination recipe (pass next_before as before), leaving nothing to inference.

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