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 that it returns both a seller profile and current listings (not historical/sold items), which is useful scope context, but says nothing about pagination, rate limits, or result caps. Baseline 3 is appropriate given annotation coverage.

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, zero waste, with the tool's core action front-loaded and the disambiguation trailing. Every clause earns its place.

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?

An output schema exists, so return-value explanation is not needed, and annotations cover the safety profile. The description is nearly complete for a read-only profile-plus-listings tool; the only minor gap is that returning listings implies possible pagination that goes unmentioned.

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 all 11 parameters (including filter enums and price bounds) are already fully documented in the schema. The description only summarises the filter categories, adding no syntax or semantics beyond what the schema provides. Baseline 3 is correct when the schema does the heavy lifting.

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') and resource ('Depop seller profile and current listing items') keyed by `username`, and explicitly names the sibling tools it is not (depop_search, depop_item, depop_search_sellers). An agent can distinguish it from siblings without opening any schema.

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 second sentence routes the agent to alternatives for adjacent tasks (finding listings, a single listing, finding sellers), giving clear context for when this tool is not the right pick. It doesn't explicitly state a when-to-use condition for this tool itself (e.g. 'use when you already have a seller username'), so it falls just short of the 5 bar.

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