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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), so the bar is lower. The description adds a genuinely useful behavioral trait not present in structured data: '1 point per returned record', a cost/billing disclosure an agent should weigh before setting max_items.

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?

A single tight sentence with the return payload and cost front-loaded, followed by the input locator. No filler, though it is sparse rather than richly structured.

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 list tool with full annotation coverage, 100% schema coverage, and no output schema, the definition tells the agent what it returns (handle, name, avatar), what it costs, and how to target the closet. Pagination behavior is left entirely to the schema, which is acceptable here.

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 the schema already documents user, domain, max_items, and start_page. The description only echoes 'by username or URL', adding nothing about domain, pagination, or limits beyond the schema. 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?

States a specific verb+resource and direction: 'Users a Poshmark closet follows', which distinguishes the follow direction from the sibling run_poshmark_users_followers. It also names the returned fields. It stops short of explicitly naming that sibling, but the direction 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?

The phrase 'by username or URL' implies the input context, but there is no explicit when-to-use guidance and no alternatives or exclusions named (e.g., contrasting with run_poshmark_users_followers or run_poshmark_users). Usage is implied rather than stated.

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