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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds that the response is the full document including lines, taxes, terms, payments and status, which is useful given there is no output schema, but it says nothing about not-found behavior for a bad id or whether payments/refunds are nested under the parent bill.

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 compact clauses with zero waste: content scope first, then the endpoint template. Nothing redundant and no filler.

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 enumerates the returned sections (lines, taxes, terms, payments, status), which is what an agent needs to decide whether one call suffices. The only gap is the absence of error/missing-id behavior for a two-required-param mutating-free lookup.

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 both parameters are already documented. The description restates the type enumeration in prose ('a bill, order, goods received note, credit note, payment or refund') and gives the URL pattern /purchases/{type}/{id}, which confirms the two params compose a path but adds no constraint beyond the schema.

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 ('One purchase document in full') and enumerates what the document contains, so an agent knows exactly what comes back. It is not explicitly contrasted with its nearest sibling, bukku_get_sales_document, though the 'purchase' framing and type list make the domain clear.

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?

Usage is only implied: fetch a single document by type and id, as opposed to the list_* siblings. There is no explicit guidance on when to prefer bukku_list_purchase_documents or bukku_list_purchase_bills, and no note that a valid id must first be obtained from a list call.

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