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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), and the description adds genuinely new behavior: the return is a flat map of fields plus a `url` field only when a public URL pattern exists. It does not say what happens on a missing id (error vs. empty), which keeps it short of a 5.

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 first two paragraphs are tightly front-loaded and earn every word. The long per-collection field inventory is largely irrelevant to a tool that only takes a collection and an id — those filterable properties belong to query_collection — so a substantial fraction of the description is padding for this call site.

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 annotations covering safety, an output schema covering return shape, and full schema coverage on four parameters, the description supplies the missing pieces: valid collection names, sibling routing, and the conditional `url` decoration. Only the not-found/error behavior is left unstated.

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%, so the baseline is 3, but the description adds real value by enumerating the actual valid collections (articles, comparisons, extension, releases, roundups, showcase), which corrects the misleading schema examples "blog" and "products" that do not exist in this list. The per-collection property lists are tangential to a get-by-id call, so the added meaning is uneven rather than complete.

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?

States a specific verb and resource ("Fetch a single object by its id from a collection") and immediately differentiates itself from query_collection and search_collection by declaring it does not search or filter. An agent can select it without opening any schema.

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?

Explicitly names both alternatives and the conditions that select them: query_collection for paginated lists, search_collection for free-text search. The id parameter description also routes the agent to those tools for discovering candidate ids, closing the loop on how to use this tool successfully.

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