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

Annotations already declare readOnlyHint and destructiveHint=false, but the description adds real value: it explains that findings follow each ad squad's goal, that the tool only suggests pausing rather than acting, and what the default time window and campaign scope are. It stops short of describing result limits, ranking, or output shape, which is the remaining gap.

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?

Four short sentences, front-loaded with the trigger, then the return criteria, then the safety note and defaults. Nothing is redundant with the schema beyond a minor restatement of the default period.

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 seven-parameter read-only analysis tool with no output schema, the description covers trigger, detection logic, goal-dependence, and default scope. What an agent might still want — how many ads come back, ordering, or the card contents — is unstated but not essential to calling it correctly.

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 all seven parameters are already documented, and the description mostly restates the LAST_14_DAYS default already present in the date_range schema. It does contribute one non-schema default (active campaigns only), but adds no syntax or interaction detail for folder/account/campaign or the start/end date pair.

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 and resource ('which Snapchat ads are wasting money') and enumerates the three detection criteria: zero-result spend, cost per result far above the ad squad average, and very low swipe rate. The Snapchat prefix and ad-level granularity clearly separate it from snapchat_performance and the other platforms' *_wasted_spend siblings.

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?

Opens with an explicit trigger ('Use this when the user asks which Snapchat ads are wasting money') and adds a default scope of last 14 days on active campaigns. It does not name an alternative for adjacent questions (e.g., ad-squad-level or campaign-level diagnostics), so routing is implied rather than spelled out.

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