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

Annotations already cover safety (readOnly, idempotent, non-destructive, closed-world), and the description adds real context on top: the call is free, it precedes the paid routes, and it enumerates the returned fields. It stops short of stating auth requirements beyond "free" or any rate limits.

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?

Three short sentences, front-loaded with the cost fact ("Free."), then the payload, then the action directive. No sentence is wasted and the ordering guidance lands last where it is most actionable.

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?

No output schema exists, and the description compensates by naming the returned fields (routes, prices, payTo, network, facilitator, payment methods). With zero params and annotations covering safety, nothing an agent needs to call this correctly is missing.

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 takes zero parameters, so the baseline is 4 and there is no parameter meaning for the description to carry. The description correctly implies no inputs are needed by presenting it as a call-first discovery tool.

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?

Specific verb plus resource: returns gofetch's paid routes, prices, payTo, network, facilitator, and accepted payment methods (x402 v2, USDC on Base). The contrast with the only sibling, gofetch_extract, is implicit rather than stated, so it just misses the top band.

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?

"Call this first" gives an explicit ordering directive that an agent can act on without inference. It does not name when-not to call it or point at gofetch_extract as an alternative, which keeps it out of the 5 band.

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