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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description usefully adds daily granularity and default-scope behavior, but with no output schema it never clarifies what 'performance' actually contains (metrics returned), leaving the agent guessing at the payload.

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?

A single sentence, front-loaded with the primary purpose and granularity, with zero filler. Every clause earns its place.

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 moderately complex six-parameter read tool with no output schema, the description covers selection scope but says nothing about the return shape or what 'daily performance' fields an agent will get. Annotations cover safety, so it is adequate but leaves a meaningful gap.

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 83%, so the schema already documents since/until/objectId/accountId/profileId. The description only restates objectId's role ('or for one campaign, ad set or ad when objectId is given') and adds nothing about date-range or account resolution beyond what the schema provides. Baseline 3 is appropriate.

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 ('Return daily performance') plus the granularity scope (account, campaign, ad set, or ad) and the condition that selects the finer granularity ('when objectId is given'). An agent can distinguish this from structural tools like ads_get_tree, though it doesn't name any sibling explicitly.

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?

Implies usage context by describing the objectId drill-down and default account-wide scope, but gives no explicit when-to-use/when-not guidance and never contrasts with alternatives such as ads_get_tree or the platform-specific insights siblings.

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