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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, but the description goes further by adding the API key requirement, the caveat that nothing changes until the user acts, and the warning about third-party content not being verified. This adds genuine behavioral context beyond the annotations.

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 well-structured in three short paragraphs: what it does, when to use it, and a trust caveat. Each sentence earns its place, though the explanation is slightly more expansive than strictly necessary for such a simple tool.

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 one-parameter, read-only tool with rich annotations and no output schema, the description covers the essential context: purpose, usage step in a workflow, authentication, and risk caveat. It is fully complete for an agent to decide when and how to invoke it.

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?

The only parameter, item_id, is fully described in the schema as 'Marketplace item ID'. The description does not add additional parameter-level detail, but this is acceptable because schema coverage is 100%, so the baseline score of 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?

The description clearly states the tool retrieves one marketplace listing in full, including preview, author, and installation instructions. It distinguishes itself from list_marketplace_items by focusing on a single item, so the purpose 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?

It explicitly instructs to use this tool after list_marketplace_items to inspect a template before adoption, and clarifies that it is a read-only step that does not install anything. This provides strong contextual guidance and differentiates it from mutation tools.

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