Measured breakdown

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

Annotations already declare a read-only, non-destructive, open-world read. The description goes beyond them by disclosing the provider ('Avada ChatGPT Ads, preview API') and the required AVADA_API_KEY credential, plus an explicit failure-mode rule about reporting the unavailability reason instead of fabricating or zero-filling figures.

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?

Three short sentences, front-loaded with what the tool returns, then source/credential, then the integrity rule. Every sentence carries information; only the phrasing 'If it answers unavailable' is slightly loose.

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 3-parameter tool with no output schema, the description should say something about the returned breakdown shape (per-dimension rows and which metrics). It covers credentials and data-integrity behavior well but leaves the response structure unspecified.

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?

With 67% schema coverage, the two date parameters are already documented in the schema. The description adds the missing meaning for the enum-typed 'dimension' parameter by enumerating its meaning as country, device or platform segmentation.

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 opening sentence names the resource (delivery metrics) and the three breakdown dimensions, which is a specific, actionable purpose. It does not explicitly differentiate itself from the sibling measurement_get_ads_report, so an agent must infer the split between breakdown vs. whole-report.

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 rather than stated: you call it when you need delivery segmented by country/device/platform. There is no explicit when-to-use or when-not-to-use, and no named alternative (e.g. the ads report sibling) for totals instead of breakdowns.

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