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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds materially by disclosing the paid model — $0.02 per call settled in USDC on Base via x402 — which an agent must know before invoking, plus the shape of returned data. No rate limits or failure modes are described.

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 sentences, front-loaded with what the tool returns and closing with the cost and payment mechanism. Dense but waste-free; the long enumeration of returned fields is the only mild readability cost.

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 read-only search with no output schema, the description covers the return contents, the maximum result count, and the payment prerequisite — the critical unknowns. It lacks any note on result ordering, pagination, or what happens when no listings match.

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% and enums are documented inline, so the schema carries the parameter burden. The description adds only the 'up to 100 listings' ceiling, which restates the schema's max of 100 rather than adding new meaning. Baseline 3 is appropriate.

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 verb and resource — live Poshmark US fashion resale listings for a keyword — and enumerates the returned payload (market summary, up to 100 listings with price, brand, size, condition, likes). The parenthetical identifies the marketplace, which implicitly separates it from vinted_search and ebay_market, but no explicit sibling comparison is made.

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 context is implied by 'keyword' search and the named marketplace, and the $0.02 per-call cost gives the agent a reason to be selective. However, there is no explicit guidance on when to choose this over vinted_search or ebay_market, nor any statement of when not to use it.

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