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

Annotations already declare readOnlyHint=true and idempotentHint=true, so 'Read-only' merely repeats structured data. The description does add value by disclosing scope behavior (empty campaign_id covers all campaigns) and the paste-ready 'block' output format, though return shape is also covered by the output schema.

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 tight sentences with the core purpose front-loaded and no filler. The trailing 'Read-only' phrase is redundant against the annotations, but the cost is a few words.

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?

For a two-parameter read tool with annotations covering safety and an output schema covering return values, the description supplies the key scope rule and workflow link. Minor gap: customer_id's meaning and whether the schedule applies to all campaign types is left unstated.

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 0%, so the description must compensate. It explains campaign_id's empty-string semantics clearly but says nothing about customer_id, leaving one of two parameters undefined in both schema and description.

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 ('Reads'), resource ('a campaign's CURRENT ad schedule'), and enumerates the returned fields (day/hour blocks, minutes, bid modifier, criterion_id). It also implicitly contrasts with the write-side sibling set_ad_schedule, so an agent can distinguish it without opening the 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?

Gives a conditional for campaign_id ('If campaign_id is empty, covers all campaigns') and hints at the read-then-write workflow with set_ad_schedule, but never states when to prefer this over alternatives or any prerequisites/exclusions. Usage is implied rather than prescribed.

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