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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so safety is covered. The description adds genuinely useful context beyond that: it names the underlying GET /advanced-purchase?ID= endpoint and clarifies that this single vendor endpoint serves every purchase type, which an agent could not infer from the schema.

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?

Front-loaded with the core action ('One purchase by id'), followed by a dense but relevant field list and a parenthetical on the backing endpoint. The long enumeration earns its place by previewing the return payload, though it is slightly heavy in one sentence.

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 no output schema, the description usefully compensates by listing the returned fields (supplier, addresses, order lines, payments, attachments, etc.). Combined with annotations covering the read-only profile, an agent has enough to call it correctly, though auth/permission expectations are 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% and both parameters are documented in the schema itself, so the schema carries the load. The description adds no syntax or format detail for purchase_id or combine_additional_charges, 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?

States a specific verb (get) and resource (purchase) scoped to a single record by id, and explicitly enumerates the covered subtypes (simple, advanced, service purchase). This cleanly separates it from cin7core_list_purchases, which returns collections.

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' framing and the note that this endpoint 'serves every purchase type' imply when to reach for it versus list_purchases, but no explicit when-to-use or when-not guidance is given. Usage is inferable rather than stated.

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