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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety profile is covered. The description adds one genuinely non-obvious behavioral trait: only approved products are retrievable, and it sketches the payload (title, plain-text card, url, website/category/pricing metadata). It doesn't say what happens for an unknown or unapproved slug.

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, front-loaded with the resource and key, then the return contents. Nothing is redundant with the tool name and no filler is present.

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?

With an output schema and full annotation coverage, the description only needs to convey scope and how to obtain the argument, which it does. The one gap is not-found / not-approved behavior for a slug that yields nothing, which matters for a fetch-by-id tool.

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 single `id` property already documents itself as 'a product slug from search or list_products'. The description restates that same fact rather than adding formatting, length, or lookup semantics beyond the schema, so baseline 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 names a specific resource (one approved product on Neeed Directory) and its retrieval key (id / slug), plus what it returns, which is far more than the generic name 'fetch' conveys. It also points to search and list_products as the source of the identifier, implicitly distinguishing this from those listing tools. Slightly fragmentary wording ('One approved product ... by id') keeps it below a 5.

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 tells the agent where the id must come from ('the slug from search or list_products'), which is a useful precondition that prevents a common misuse. It stops short of an explicit when-to-use statement (e.g. 'call this when you need full detail for a known product rather than a list of candidates').

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