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

Annotations already declare readOnlyHint=true and idempotentHint=true, and the description does not contradict that. It adds useful behavioral context by warning that output is bounded by project size and can be heavy on large projects, which is real information beyond the annotations.

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 concise and front-loaded: first sentence states what it does, second positions it among siblings, third gives practical guidance. Every sentence earns its place without fluff or repetition.

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 read-only/idempotent annotations, complete input schema coverage, and the description's mention of output scope, an agent has enough context to select and call the tool correctly. It does not describe an exact response shape, but for an invocation-focused tool and with no output schema required, this gap is minor.

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?

The schema already documents all three parameters with 100% coverage, so the description does not need to restate them. It does add the useful caveat that shorter dateFrom/dateTo ranges are preferable for large projects, but it does not deepen the meaning of the individual parameters beyond the schema.

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 opens with a specific verb and resource: "Returns the full stats breakdown of a single project," and details the granularity as "every Riddle in it, down to blocks, choices and form fields." It also distinguishes itself from stats_user_breakdown and stats_riddle_breakdown, making its role clear among siblings.

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?

It explicitly frames this tool as the drill-down from stats_user_breakdown's account-wide summary, which tells an agent when to reach for it. It also provides conditional guidance: for large projects prefer a shorter date range, or use stats_riddle_breakdown for individual Riddles.

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