compare

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

Annotations already cover safety (readOnlyHint, destructiveHint=false, closed world), and the description adds genuinely useful behavioral detail beyond them: the comparison is descriptive, and a null percent change signals a zero baseline. It does not state permissions or limits, but for a read-only comparison this is largely covered.

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 short sentences, front-loaded with the core action and followed by the edge-case semantics. Nothing is wasted or repeated from structured fields.

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?

An output schema exists, so return values need not be documented, and the null-percent-change note covers the main interpretive edge case. The only real gap is the undocumented 'days' parameter, which an agent would have to infer from the period framing.

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 0% and the single 'days' parameter (default 30) is never mentioned; only the abstract notion of an 'equal-length previous period' hints at a duration window. The description adds conceptual framing but does not document the parameter's meaning, units, or default.

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?

Names a specific verb (compare) and the resource/scope: traffic, custom events, and revenue over an equal-length previous period. It clearly states what is produced without restating the tool name, though it does not explicitly differentiate itself from siblings like breakdown or revenue_attribution.

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?

"Compare an equal-length previous period" implies the context of use (comparing current vs prior period), but there is no explicit when-to-use/when-not guidance and no sibling alternatives are named, leaving routing up to inference.

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