Global app share

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

Annotations already declare readOnlyHint, idempotentHint and non-destructive, so safety is covered. The description adds meaningful behavior beyond that: a fixed 30-day window, an all-shows aggregation scope, and the ability to narrow to a single device.

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 scope and time window, each carrying information. 'It is useful on its own' is slightly padded but not wasteful.

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?

Discloses the fixed time window, the aggregation scope, and device narrowing, and the schema fully documents the two optional params. Without an output schema, a brief note on the return shape (app names + share percentages) would round it out.

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 both optional params are already documented in the schema. The description adds only mild context about what narrowing by device reveals, 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: 'Podcast app market share across every show OP3 measures, over the last thirty days.' It also explicitly distinguishes itself from a per-show tool ('not one show's numbers'), which is critical given the sibling op3_app_share.

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?

Gives clear usage context ('useful on its own for questions about the podcast app landscape') and contrasts with per-show data. It stops short of naming the alternative tool (op3_app_share or op3_benchmark_apps), so the routing is implied rather than explicit.

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