Compare Periods

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

Annotations declare readOnlyHint=true, and the description confirms a read-only comparison operation. It adds contextual value by listing specific returned metrics (revenue, cost, ROAS, etc.) and percentage changes, which are not in the schema. There are no contradictions. The description does not disclose potential behavioral details like data freshness or pagination, but given the read-only nature, this is adequate.

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?

The description is two sentences: the first clearly states the tool's purpose and requirements; the second lists output metrics and a concrete use case. There is no redundant information, and every sentence earns its place. It is appropriately front-loaded and easy to parse.

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?

Given the tool's complexity (8 parameters, 6 required, no output schema), the description covers the core functionality, input requirements, and output. It lacks details about potential constraints (e.g., non-overlapping periods) or how to interpret percentage changes, but the use case example compensates partially. The presence of annotations and full schema coverage reduces the burden on the description.

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%, so baseline is 3. The description mentions 'Requires an ad account ID and level' and hints at date usage via the example, but does not add new meaning beyond what the schema already provides for each parameter. No additional constraints or format guidance are given.

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 specific verb 'Compare' and identifies the resource 'ad performance metrics between two date ranges using attribution data.' It clearly distinguishes from sibling tools like hyros_best_performers by specifying the two-period comparison and the metrics returned (revenue, cost, ROAS, etc.). The example 'compare this week vs last week' further clarifies the purpose.

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?

The description states prerequisites ('Requires an ad account ID and level') and describes what is returned (revenue, cost, ROAS, sales, leads, percentage changes). It also provides a typical use case ('Perfect for compare this week vs last week'). However, it does not explicitly mention when not to use this tool or suggest alternatives like hyros_best_performers for top-level summaries.

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