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

Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=false and destructiveHint=false, so the safety profile is fully covered by structured data. The description adds two useful behavioral facts beyond that: results come from the advertiser portal inventory and are priced. It does not mention pagination (cursor) or result scope, so it only modestly exceeds what annotations provide.

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?

Two tight sentences, verb-first, with no filler or repetition. It is appropriately sized, though for an 8-parameter tool with nested objects the brevity comes at the cost of leaving parameter guidance on the table.

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?

An output schema exists, so return values need not be explained, and annotations cover the safety profile. However, for a tool with 8 params, a nested radius object, and only 38% schema coverage, the description omits pagination behavior, source semantics, and how radius interacts with city/query (which the schema flags as mutually exclusive). Adequate but with clear gaps.

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 only 38% (city, query and radius carry descriptions), so the description should compensate and largely does not. Naming CTV/video/audio/display merely echoes the `channels` enum already in the schema, and nothing is said about source, state, cursor, limit, or the radius object semantics. With low coverage this leaves several parameters undocumented in either place.

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?

The description gives a specific verb ('Find') and resource ('local digital out-of-home screens and available CTV, video, audio and display products'), so an agent knows exactly what is being searched. It is naturally distinct from the campaign-management siblings (booking, checkout, preview, delivery) without naming them. A 5 is withheld only because the differentiation from siblings is implicit rather than stated.

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?

The phrase 'for an agency client' gives loose context, but there is no when-to-use/when-not guidance, no prerequisites, and no mention of alternatives among the eight campaign siblings. The agent must infer that this is the inventory-discovery step that precedes prepare_campaign_booking or preview_campaign_plan.

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