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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true, so the safety profile is covered. The description adds useful return-shape context - that status surfaces review/rejection states and that each ad carries text, CTA, and landing page alongside period metrics. It says nothing about pagination, result caps, or account scoping behavior, which matters for a 10-parameter listing tool with no 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?

Two clipped sentences, front-loaded with what the tool returns before the filtering note. No filler. The telegraphic style is slightly terse ('Ads with status...') but every clause carries content.

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 10-parameter, zero-required, no-output-schema listing tool, the description covers the returned fields but omits how results are scoped (account/folder defaults), what 'period performance' means without a date range, and how summary vs full detail changes output. The schema's own descriptions patch some of this, leaving the definition adequate but not complete.

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 70%, so most parameters are already documented in the schema (detail, folder, account, language, date_range, dates). The description adds meaning only for the two filter parameters (campaign, adgroup) and implicitly for status by noting review/rejection values. It does not explain the status enum, detail modes, or date-range defaults beyond what the schema states, so it is roughly at the baseline.

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 names the resource (TikTok ads) and enumerates what the rows carry: status including review/rejection, ad text, call to action, landing page, and period performance. That is more specific than the bare title. It does not differentiate itself from close siblings such as tiktok_performance or tiktok_creative_insights, so it stops short of a 5.

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?

'Filter by campaign or ad group' hints at how to narrow results but gives no when-to-use condition or when-not. With siblings like tiktok_performance, tiktok_breakdown, and tiktok_creative_insights overlapping heavily, an agent gets no routing signal for choosing this tool over those.

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