rybbit_compare_periods

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

No annotations are provided, so the description carries the safety/behavior disclosure burden. It discloses key behavior: the tool returns current/previous values, computes absolute and percent changes, and explicitly explains the percentChange null edge case. It does not explicitly mention permissions or read-only nature, but 'Compare... Returns...' strongly implies a read 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?

Two tight sentences deliver the core purpose, operation, return values, and an edge case without wasted words. It is front-loaded with the main action and easily scanned.

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 comparative analytics tool with no output schema, the description sufficiently explains the return shape and the period calculation logic. It could name the exact metrics returned, but 'site overview metrics' is adequate context given sibling tool naming and the parameter schema.

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 the baseline is 3, but the description adds meaningful context by clarifying that the provided startDate/endDate define the current period and the preceding period is automatically equal-length. This is not present in the schema and is central to correctly using the tool.

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?

Description uses specific verb 'Compare' and identifies exact resource ('site overview metrics') plus core operation (date range vs equal-length preceding period). This clearly distinguishes it from sibling get-only tools like rybbit_get_overview and rybbit_get_overview_timeseries.

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 makes the intended use case clear: comparing the current period to the immediately preceding equal-length period. It does not explicitly name alternatives or give when-not-to-use guidance, but the use case is strongly implied and distinct from the available siblings.

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