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

readOnlyHint=true already tells the agent this is a safe read. The description adds useful context by naming the returned components (lines, totals, customer, warehouse) and the underlying endpoint, but says nothing about not-found behavior, pagination, or auth/tenant requirements.

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?

One front-loaded sentence plus a compact endpoint reference; nothing is wasted. The endpoint string is mild redundancy with the tool name but aids traceability, so it just misses a 5.

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?

There is no output schema, so the description must hint at the return shape, and it does by listing lines, totals, customer and warehouse. It stops short of describing the serialBatch toggled fields or error responses, leaving a small but real gap.

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% (both orderGuid and serialBatch are documented in the schema, including the Guid pattern), so the schema carries parameter meaning. The description names the Guid key but adds no syntax or format detail and never mentions serialBatch, 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 (Fetch) and resource (a single sales order) and names the identifying key (Guid), plus what comes back. 'Single' cleanly distinguishes it from the sibling list_sales_orders without the agent opening either 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?

The word 'single' implies this is the by-id retrieval path versus the list_* siblings, but there is no explicit when-to-use/when-not statement, no mention of list_sales_orders as the alternative, and no note about what happens if the Guid is unknown.

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