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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds real value by disclosing the content shape returned (seller profile, public comments, similar items), which helps an agent decide whether this single call satisfies its information need.

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: purpose and payload scope first, workflow routing second. No filler, no repetition of the tool name, fully front-loaded.

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 isn't obligated to describe return values, yet it still summarizes the payload. The single required parameter is fully documented in the schema, so nothing needed to call this tool correctly is missing.

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 the schema itself explains the id as the trailing segment of a /listing/{slug}-{id} URL and notes the slug is cosmetic. The description only says 'by `id`' and adds no syntax or format detail beyond what the schema already provides, 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?

States a specific verb ('Fetch'), a bounded resource ('one Poshmark listing'), and the scope ('full detail by `id`'), then enumerates the payload (description, photos, size/brand/condition, seller profile, comments, similar items). This distinguishes it from poshmark_search, which only discovers IDs.

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?

Explicitly routes the agent to the sibling tool: 'Use poshmark_search to discover listing IDs,' establishing the discovery-then-fetch workflow. It stops short of stating when not to use this tool or how it differs from poshmark_closet, but the routing guidance is clear and actionable.

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