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

Annotations only declare readOnlyHint:false, leaving the mutation aspect to the description. The description discloses critical behaviors: dry_run prevents mutation, windows crossing midnight are auto-split, timezone 'local' maps differently per platform, explicit IANA zones are offset-baked with a DST caveat, and the operation is scoped to the active Space. This goes well beyond the annotation and adds rich, non-obvious context.

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?

The description is a single dense paragraph but is well-structured: it front-loads the core purpose and value proposition, then explains input formats, timezone rules, and the dry_run safety net. Every sentence adds necessary detail for a tool of this complexity; there is no fluff or repetition.

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 tool with 7 parameters, no output schema, and complex platform-specific behavior, the description covers all essential aspects: input syntax (HH:MM, day shorthands), presets, window crossing midnight, timezone handling for each platform, dry_run behavior, and scoping. It does not specify the exact return format, but dry_run is described as returning the expanded schedule and warnings, which is sufficient for an agent to call it safely.

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 coverage is 100%, so the baseline is 3. The description adds meaning beyond the schema by explaining the timezone semantics in detail (e.g., 'local' on Microsoft vs Google, offset-baking with DST caveat), the meaning of presets and window splitting, and the dry_run behavior. This elevates it above the baseline, though the schema already carries significant detail.

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 states a specific verb ('set') and resource ('campaign's weekly ad schedule'), and explicitly differentiates itself from the sibling update_campaign by calling itself 'the easy front door over update_campaign's adSchedule.' An agent can immediately tell this tool is a specialized, friendlier alternative.

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?

It gives clear when-to-use guidance ('easy front door over update_campaign's adSchedule'), explains platform-specific requirements (Microsoft vs Google timezone handling), and recommends dry_run:true for previewing without mutation. It also explains when to omit timezone and how to use presets. This is explicit and comprehensive.

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