App share

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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), so the bar is lower, yet the description adds real operational context: the three-calendar-month restriction on the competing endpoint and why download share can be inflated by re-requesting apps. It does not discuss pagination, rate limits, or how the two metrics are computed, so not a full 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, zero filler, and front-loaded: purpose first, then the routing rule versus the alternative, then the interpretation caveat. Each sentence earns its place by changing how an agent would call or read the tool.

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 some return-value burden and does name the two core columns (listener share, download share) and the windowing behavior. It stops short of describing the response shape, output format, or how windows outside the default are validated, leaving a small gap.

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 every parameter (identifier, start, end, top, bots) is already documented in the schema, establishing the baseline of 3. The description only alludes generally to 'any window you choose' and adds no per-parameter syntax or default detail beyond the schema.

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 ('which podcast apps a show's audience uses'), the scope ('any window you choose'), and the returned metrics ('unique listeners alongside downloads'). It is clearly distinguishable from the global/aggregate siblings such as op3_global_app_share and op3_benchmark_apps.

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?

Explicitly names the alternative ('OP3's built-in app query') and the exact condition that selects this tool over it ('when the window matters, because OP3's own endpoint is locked to the last three calendar months'). It also guides interpretation, telling the agent that listener share is the more honest column versus inflatable download share.

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