One artist's whole history

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

Annotations already cover read-only/idempotent semantics, and the description adds a real behavioral constraint not in the structured data: only primary-artist plays are counted, and the name path includes imported-export data. It does not discuss result size or ordering, so not a 5.

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, front-loaded with what is returned before how to call it. The output enumeration is dense but every item is a distinct aggregate, so little padding; slightly long but earns its space.

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 carries the burden of describing returns and does so explicitly; with 100% schema coverage the parameters are already documented, and usage plus the primary-artist caveat close the remaining gaps. Nothing an agent needs is missing.

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 the schema lacks: that name is case-insensitive-ish matched via the schema and, more importantly, that the name path catches imported-export plays that the id path may miss. That is genuine decision-relevant parameter context.

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?

Names a specific verb+resource ('An artist's all-time plays') and enumerates the returned aggregates (minutes, first/last play, plays per month, top songs), which cleanly separates it from track_history and top_artists. The scoping clause 'Counts only plays where they are the primary artist' pins down the resource boundary.

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?

Tells the agent how to supply the inputs (id from search, or name) and gives a decision-relevant nuance: name 'also catches plays from the imported export'. It lacks an explicit when-not/alternative-tool statement, so it stops short of 5.

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