Audience summary

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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the bar is lower. The description adds genuine interpretive context the annotations cannot: how to read downloadsPerListener, that values near 1 mean distinct people, and that higher values mean re-requests that inflate download counts elsewhere. It doesn't cover pacing/cost beyond the schema's note about raw rows.

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?

Purpose is front-loaded in the first clause and every sentence carries information. The second sentence is long and slightly rhetorical ("the number OP3's own dashboard ... cannot give you"), which costs a little tightness but not clarity.

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 must carry return-value meaning, and it does explain the key figure (downloadsPerListener) and its interpretation. It leaves the rest of the response shape unspecified, but for a read-only summary over a well-documented schema it is largely complete.

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 all four parameters are already documented in the schema (window formats, bots default, identifier types, slowness warning). The description adds no parameter-level detail beyond what the schema carries, so the baseline of 3 applies.

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+scope: unique listeners vs downloads for a show over any window, and explicitly distinguishes the result from what other rolled-up endpoints return. An agent can tell this apart from op3_show_downloads and op3_query_downloads 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?

Strong implicit routing: it says this is what the dashboard and every rolled-up endpoint cannot give you, telling the agent to reach for it when it needs people rather than requests. It stops short of naming the specific sibling to use instead (e.g. op3_show_downloads) when raw download counts are wanted.

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