compare_periods

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

No annotations are provided, so the description carries the full burden. It discloses the core behavior (comparing periods, calculating absolute and percent change), explains the implicit baseline behavior (omitting baseline uses the prior window), and describes how series are matched with a breakdown. While it doesn't detail edge cases like overlapping periods or resolution, it provides enough transparency for a read-style analytics operation.

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 concise paragraphs. The first front-loads the purpose and core usage, including the key interaction between current and baseline. The second adds one clarifying detail about breakdowns. No filler or redundant information, making it exceptionally efficient.

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?

The description effectively covers the tool's purpose, usage patterns, and key parameter semantics. Even though there is no output schema, the description implies the return structure ('absolute and percent change per series', 'which platform or country actually moved') which adequately hints at the output. Minor omissions like pagination or limit behaviors are acceptable for this analytics context, but it could still be slightly more explicit.

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 the baseline is 3. The description adds value beyond the schema by explaining the interplay between current/baseline time parameters, the rule for 'baselineStartTime' omission, and how breakdown series are matched by label. These contextual hints help the agent correctly populate parameters, raising the score to 4.

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 clearly states the tool compares metrics between two time ranges and reports absolute and percent change per series. It identifies a specific use case (measuring effects of updates/events/marketing) and distinguishes itself from sibling metrics tools by emphasizing the comparative analysis aspect.

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 explicitly instructs when to use the tool (to measure changes) and explains how to set the current and baseline periods, including the rule for omitting the baseline to use the immediately preceding equal-length window. It also briefly explains breakdown matching. However, it does not name alternative tools or state explicit when-not-to-use cases, so slightly less than a 5.

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