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

No annotations are provided, so the description carries the full behavioral burden. It discloses the 'top 30' truncation, which is useful, but does not explain the 'PRO.' gating requirement, what auth is needed, or what the result shape looks like for a subscription-gated stats call.

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 clauses with no waste and the aggregation scope front-loaded. The cryptic 'PRO.' token is the only piece that costs the reader without paying back in clarity.

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 one-parameter stats tool with full schema coverage and no output schema, the description covers the aggregation and its cap. It falls short on access gating and usage context, which an agent needs to invoke it correctly.

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?

There is a single parameter with 100% schema description coverage, so the schema already documents access_token. The description adds nothing about authentication semantics beyond the bare 'PRO.' hint. Baseline 3 applies when the schema does the heavy lifting.

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?

States a specific resource and aggregation: sponsor counts grouped by route and by town, limited to top 30. An agent can tell this is an aggregate stats tool, though the name 'register_stats' doesn't align with 'sponsors' and no sibling (sponsor_search, sponsor_check) is named as the non-aggregate alternative.

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 only contextual cue is the 'PRO.' prefix, which implies a subscription gate but never explains it. There is no guidance on when to use this versus sponsor_search or b_rated, nor on choosing between route and town grouping.

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