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

Beyond the readOnlyHint annotations, the description discloses authentication behavior: passport sign-in via Authorization header or passport_token unlocks update_available and owner promo data. It also clarifies null behavior for update_available when no newer free version exists.

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 core purpose is front-loaded in the first sentence. The remaining sentences are dense but each carries relevant conditional-return information, though the long nested clause about update_available could be easier to parse.

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?

The description covers authentication and special owner-specific fields, but without an output schema it does not fully describe the general item payload or error/not-found behavior. It is adequate for invocation but leaves return-value expectations partially vague.

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 already 100%, so the schema documents both parameters. The description still adds useful semantic context for passport_token by explaining that it substitutes for app sign-in and changes which owner-specific fields are returned.

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 states a specific retrieval action: 'Full details of one item by slug.' It distinguishes this lookup from search_catalog by noting that search_catalog always shows the general offer while this tool can show owner-specific promo and update_available data.

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 slug parameter is tied to search_catalog, which gives clear usage context, and the description explains when passport-authenticated calls reveal additional owner-specific information. It does not explicitly state when not to use this tool, but the intended lookup vs. search flow is clear.

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