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

Annotations already declare readOnly, idempotent, openWorld, and non-destructive, so the safety profile is covered. The description still earns credit by disclosing the default status filter of 'open' — a behavior that silently hides expired, cancelled, and filled listings — and by explaining the cursor/nextCursor pagination contract, neither of which the annotations convey.

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 compact sentences, with the resource identity front-loaded and the operational details (optional filters, status default, pagination) following. Nothing is redundant with the title and no sentence is filler.

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 an eight-parameter, zero-required read list endpoint with no output schema, the description covers the essentials an agent needs to call it correctly: default filtering and how to paginate. The remaining gap is the opaque filter semantics (wantType, class enums), which would matter for a caller building targeted queries.

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 description adds genuine meaning beyond the schema by explaining the pagination loop ('Use `cursor` from `nextCursor` for the next page'), which references an output field absent from the input schema. However, with only 50% schema description coverage, several parameters (wantType, wantClass, offerClass, cursor itself) carry no explanation in either place, and the description does not compensate — notably it never explains what class values A/B/C/D/X mean.

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 names a specific resource ('Listings of the circle's marketplace') and clarifies the domain precisely: 'what an account offers and what it wants.' Coupling that with 'read API GET /listings' makes the operation unambiguous. It does not explicitly contrast itself with siblings like x207_member_inspect or x207_order_status, but the resource is distinct enough that confusion is unlikely.

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?

It states that filters are optional and that `status` defaults to open, which is real usage guidance for a caller who might otherwise assume all statuses are returned. It does not say when to prefer this over sibling tools or when a filtered query is more appropriate than browsing, leaving selection to inference from the resource name.

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