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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint false. The description adds value beyond that by disclosing the cost ($0.01 USDC per successful call) and the methodology (inflow across comparable windows). It doesn't detail response format or failure behavior, but the annotation coverage lowers the burden.

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 sentences: the first states the core purpose with a specific metric, the second states pricing. No filler or redundant terms.

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 simple, one-optional-parameter read-only tool, the description covers the core behavior and cost. It does not describe the output shape, and there is no output schema, but the name and purpose imply a list of services. Slight ambiguity around 'comparable windows' remains, but overall sufficient.

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 single `limit` parameter is 100% documented in the schema with min, max, default, and description. The tool description adds no parameter-specific detail, so the baseline 3 applies.

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 identifies the resource (x402 services) and the selection criterion (growing now by observed inflow across comparable windows). It avoids tautology and gives a specific measurement basis. It lacks an explicit imperative verb like 'list' or 'return', which keeps it from a 5.

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 on when to use this tool versus siblings like x402_top_movers or x402_new_entrants. The description explains what it does but not when it should be preferred, nor does it name alternatives or exclusions.

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