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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the description earns credit for what it adds beyond them: it discloses the analysis criteria and clarifies that the tool only suggests what to pause or fix rather than acting. It does not state how thresholds are defined (what counts as 'very high' CPR or 'low' CTR) or how results are ordered, which keeps it below a 5.

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?

One front-loaded sentence states the purpose and the detection criteria, followed by a short clause on read-only behavior and recommendations. There is no filler, though the semi-colon construction packs three criteria into a single long clause rather than structuring them for scanability.

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 7-parameter, all-optional diagnostic tool with no output schema, the description covers what is found and the nature of the output (suggestions rather than mutations). The remaining gaps (threshold definitions, tie-in to the detail enum's summary versus full modes) are minor given the fully documented schema and the read-only annotations.

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%, with the detail, language, date_range, account and folder parameters all documented in the schema itself, including the default detail mode and the default LAST_30_DAYS range. The description adds no parameter-level guidance beyond the schema, 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?

The description uses a concrete verb ('Find') and defines the resource precisely by enumerating the three failure criteria it detects: spend with zero results, very high cost per result versus the account average, and low CTR. This clearly separates it from a generic metrics tool like tiktok_performance, though it never names a sibling outright.

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?

Usage is implied by the framing ('money spent without results', 'suggests what to pause or fix'), which tells an agent this is for diagnosing inefficiency rather than general reporting. However, there is no explicit when-to-use statement, no exclusion pointing to tiktok_performance or tiktok_breakdown for broader analysis, and no note about prerequisites such as an enabled account.

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