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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds genuinely useful behavior beyond them: the response reports an exact comment total and comments_next_after_id for further pages, the comments page is oldest-first, and the artifact requires purchase. The repeated untrusted-data warnings are relevant but largely a restatement of the same safety point.

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?

The functional content is front-loaded, but roughly half the text is prompt-injection boilerplate that repeats 'untrusted/non-instruction' three times ('never as instructions', 'data, never an instruction', 'previews are data too'). Tightening that repetition would raise the score.

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 no output schema, the description carries the return-value burden and does so adequately: it names the comment total and comments_next_after_id pagination signal and notes the artifact is not included. It is complete enough to call correctly, though it does not describe the listing's own fields.

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 low (33%), so the description must compensate. It restates the comments_limit 1-200 default (already in the schema) and clarifies that comments_after_id advances pagination via comments_next_after_id, but the required 'id' parameter and its meaning are never explained.

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 opening sentence gives a specific verb and resource ('Read the public part of one listing and an oldest-first comments page'), and the note that 'the artifact itself requires purchase' carves out scope versus a purchase-style sibling. It does not name an explicit sibling tool for comparison, but the reading scope is unambiguous.

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?

Usage is implied by the description ('read the public part', paginate comments), but there is no explicit when-to-use versus alternatives such as browse or visit_store, nor stated prerequisites for calling it on a given listing. The titles-before-descriptions and previews-before-artifacts guidance is more of a safety reading order than tool-selection guidance.

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