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

Annotations already declare readOnlyHint=true (safe read) and openWorldHint=true (output may be partial). The description adds that the statistics are 'index-level' and lists covered categories (services, verification breakdown, data freshness). This provides behavioral context beyond annotations without contradiction.

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?

A single, concise sentence that front-loads the purpose and key categories. Every word adds value; no fluff. Ideal length for quick comprehension.

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?

With no output schema, the description carries full burden of explaining return values. It lists three categories, which is sufficient for an AI to understand what the tool returns. However, it omits details like whether results are aggregated or per-index, and whether there are any filters. Still, given the tool's simplicity and zero parameters, the description is largely complete.

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 tool has no parameters and the schema description coverage is 100%. The rule states baseline 4 for 0 parameters. The description does not need to add parameter semantics, and it doesn't, which is appropriate.

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 clearly states that the tool provides 'Index-level statistics' and specifies the content categories: services, verification breakdown, and data freshness. This distinguishes it from siblings like 'check_wallet', 'find_paid_service', and 'get_service' which target specific resources. The verb is implied but the resource and output granularity are unambiguous.

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?

No guidance is provided on when to use this tool versus its siblings. While the title and description suggest a general overview tool, there is no explicit 'use this for aggregate stats, use find_paid_service for searching' differentiation. The agent must infer usage context from the empty parameter list and sibling names.

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