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

Annotations already declare readOnly, idempotent, non-destructive, open-world behavior, so the safety profile is covered. The description adds one genuinely new fact beyond them — the required items.read scope — but says nothing about what happens on a missing id (404 vs empty) or how embed scopes affect the reply.

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 short sentences with zero filler; the operation is front-loaded and the auth prerequisite follows. Every sentence carries usable information.

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 single-record fetch with a fully described schema and no output schema, the description covers the essentials plus the required scope. The only gap is failure behavior on an unknown id, which is minor for this tool class.

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 description coverage is 100%: id, embed (with extra-scope caveat and examples) and field (with projection examples) are all documented in the schema. The description adds no parameter meaning, so the 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?

"Get one catalog item by id" names a specific verb and resource and scopes it to a single record, which implicitly separates it from sellsy_list_items and sellsy_search_items. It stops short of naming those siblings explicitly, so an agent must infer the routing.

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 "by id" phrasing implies you already know the item id, which weakly signals when to prefer this over a list/search tool. No explicit when-not guidance or named alternatives are given.

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