marketplace_check_endpoint

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

With no annotations, the description carries the full burden and does so reasonably well: it is free, non-submitting (a precheck), runs the same live check the review queue runs, and defines the success condition (compliant=true only when a 402 envelope with facilitator and accepts fields is served). It does not mention rate limits or what is returned on failure, but the safety profile is clear enough from "precheck" and "free".

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 use case, then the success criterion, then the input constraint. Every sentence adds information and none repeats the schema.

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, annotation-free check with no output schema, the description covers what is checked, what success looks like, and an input restriction. The only gap is what happens on a non-compliant result (e.g., whether diagnostic detail is returned).

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?

Schema coverage is 0%, so the description must compensate, and it does with the constraint "https:// URLs only" – a real input restriction absent from the bare string schema. The single parameter's meaning (the endpoint to check) is obvious from its name and the description's context.

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 action (live x402 compliance precheck) on a specific resource (an endpoint URL) and ties it to marketplace submission, so an agent can tell it apart from generic checks like preflight_check or check_facilitator_liveness. It does not explicitly name a sibling it is not, such as check_x402_endpoint, which is the closest neighbor.

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?

"Free precheck before submitting to the AgentPayStore marketplace" gives a clear when-to-use trigger and implies the follow-on action (marketplace_submit). It stops short of stating when NOT to use it or how it differs from check_x402_endpoint, so the routing decision is only partly resolved.

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