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

No annotations are provided, so the description carries the behavioral burden. It communicates that this reports on previously collected probe/crawl data rather than triggering a live operation, which is useful context. It does not explicitly state side effects or permissions, but for a zero-parameter read-only stats tool this is a minor gap.

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 sentence that front-loads the resource and then lists the report contents compactly. There is no filler, redundancy, or unnecessary detail.

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 zero-argument aggregate report with an output schema present, this description is complete: it covers the dimensions summarized and the temporal anchor ('last probe', 'when the crawl ran'). The output schema can handle return-value details.

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 zero parameters, so the baseline is 4 and there is no parameter semantic burden on the description. The description appropriately focuses on what the summary contains rather than parameter behavior.

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 names the resource ('x402 service index') and enumerates exactly what the summary contains: totals, endpoint response counts, per-network/per-source counts, and crawl timing. This clearly distinguishes it from siblings like x402_probe and x402_search, which imply live probing and searching rather than aggregate reporting.

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 does not explicitly say when to prefer this over x402_probe or x402_search, and it names no alternatives. However, the intended use is implied: use this to inspect historical index/crawl statistics rather than to perform a new probe or search.

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