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

The readOnlyHint annotation already declares this a safe read, so the bar is lower. The description usefully adds the shape of the payload (totals, customer, payment/fulfillment status), but says nothing about not-found behavior, permissions, or rate limits.

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 tight sentences, front-loaded with the core purpose and payload, with the REST endpoint mapping appended as compact reference. No filler or repetition.

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 one-param read tool with a readOnlyHint annotation and no output schema, the description covers purpose and return content well enough to call correctly. The only real gap is routing guidance against the sibling search 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% for the single parameter, and the schema already documents order_number as 'the store-visible order id'. The description's 'by its order number' adds no syntax, format, or lookup nuance beyond that, 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 gives a specific verb and resource ('Get a single order'), scoped by identifier ('by its order number'), and enumerates the included data (line items, totals, customer, payment/fulfillment status). It implicitly distinguishes itself from the sibling ecwid_search_orders via 'single' and 'by its order number', but never names that sibling explicitly.

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 implied: fetch when you already hold the order number. There is no explicit statement of when to use this versus ecwid_search_orders (lookup by known id vs. discovery/filtering), so the agent must infer the boundary itself.

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