mercari_item

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

With no annotations provided, the description carries the transparency burden. It discloses credential-free public data, an anonymous login-free session, and the Mercari mobile-app API source, plus a normalized output shape. It does not mention failure modes or rate limits, but for a simple read operation this is strong 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?

The description is two sentences with no filler. The first sentence states the action and enumerates useful output fields; the second adds essential access context. Every sentence 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?

For a single-id read tool with no output schema, this description is quite complete: it lists the main return fields, notes normalization, and explains access requirements. It omits details like error behavior and data freshness, but these are not critical for tool selection.

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 coverage is 100%: the single 'id' parameter is already described as 'Mercari item id, e.g. from a search result's id field.' The tool description adds no new parameter-level meaning beyond this, so it meets the baseline.

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 starts with a specific verb and resource: 'Get Mercari item detail.' It then enumerates the exact returned content (description, photos, price, condition, category, hashtags, shipping origin state, similar items), making it clearly distinct from sibling search tools like mercari_search.

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 description implies usage after obtaining an item id, and the schema's 'e.g. from a search result's id field' reinforces that context. However, it does not explicitly name alternatives or state when not to use this tool, so it stops short of fully explicit guidance.

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