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

Annotations already declare readOnlyHint, idempotentHint, non-destructive, and openWorld, so safety is covered structurally. The description adds genuine behavioral value beyond that by stating no sats are spent and no listing is published, and by disclosing that it returns a prefilled draft rather than a live listing.

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 action and outcome first, then the side-effect exclusions. Front-loaded, no filler, and each clause carries weight. Not maximally tight, but efficient and well-ordered.

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 an output schema present, the description need not explain return values, and parameters are fully covered by the schema plus rich annotations. The description supplies purpose and side-effect constraints, leaving only the sibling-routing decision unaddressed, which is a minor gap.

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 description coverage is 100%, so both parameters are already documented (endpoint_url and http_method with its enum and GET default). The description adds only the 'public https' constraint on the endpoint, which mostly restates the schema, so 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 gives a specific verb (probe), resource (one public https endpoint), and two concrete outcomes (an L402 challenge and a prefilled listing draft). It also implicitly distinguishes itself from write/spend siblings by clarifying it does not spend sats or publish. The title/name 'List my endpoint' is slightly misleading versus the actual 'probe' action, which keeps this 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?

The negative statements ('does not spend sats', 'does not publish the listing') imply when-not to expect side effects, which is useful context. However, there is no explicit when-to-use guidance and no named alternative among the siblings (e.g. report_sku or buy), leaving selection largely inferred.

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