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

Annotations already indicate this is read-only and non-destructive, and the description does not contradict them. It adds useful behavioral context by specifying what the fetched manifest contains: seller profile, offers, and actions.

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?

One sentence with no filler. The verb and target resource are front-loaded, and the parenthetical clarifies the return contents without bloating the description.

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 simple read-only tool with one required parameter, the description is nearly complete: it states the input and the expected return contents. It could be slightly stronger by noting behavior for unknown slugs or pointing to discovery tools, but these are minor gaps.

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% and the slug parameter is already described as 'Listing slug'. The description adds 'by slug' but no additional format, uniqueness, or sourcing details beyond what the schema provides.

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 uses a specific verb ('Fetch'), names the resource ('a listing's full structured agent manifest'), and scopes it by slug. This clearly distinguishes it from sibling discovery tools like nexez_directory and nexez_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 phrase 'by slug' implies this tool should be used when the agent already has a slug and needs the full listing manifest. However, it does not explicitly state when to prefer this over sibling tools, such as using nexez_search when the slug is unknown.

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