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

Annotations already declare readOnlyHint=true, and the description is consistent with it. It adds genuine value beyond the annotation by fully specifying the return shape and metric semantics (visitors = unique converters, events = total conversions, conversion_rate = converters as a percent of all visitors), plus the period scoping. Minor gaps: no disclosure of empty-result behavior or error cases, but acceptable for a read-only report tool.

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 efficient sentences: the first states the purpose, the second defines the return contract. Every element earns its place, and the purpose is front-loaded ahead of the example.

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?

There is no output schema, so the description correctly compensates by fully documenting the return JSON and each metric's meaning. All three optional parameters are schema-documented, and the read-only safety profile is covered by annotations. Nothing an agent needs to call this correctly is missing.

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 schema already documents site, limit, and period fully. The description adds only marginal parameter context — tying the conversion_rate definition to 'all visitors in the period', which reinforces the period parameter. This matches the baseline 3 where the schema carries the load.

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 states a specific verb+resource: 'The site's configured goals ranked by conversions'. The embedded return-format example with the event:goal dimension and conversion_rate metric makes the purpose unambiguous and clearly distinct from siblings like list_goals (plain listing), create_goal, or query_stats.

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 implies usage context — you call this when you want conversion-ranked goal data for a site — but it never explicitly says when NOT to use it or names alternatives among the 25 siblings (e.g., query_stats, funnel_report). No exclusions are given, leaving routing to inference.

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