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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds useful return-shape context (lines, supplier, totals), but says nothing about error behavior for an invalid/unknown Guid, auth requirements, or rate limits, so it does not go far beyond the annotation baseline.

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 with zero filler: the primary capability and scope are front-loaded, and the endpoint reference is appended compactly. Every clause earns its place.

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 single-resource read tool with annotations covering safety and a fully documented parameter, the description is nearly complete; it even summarizes the return payload despite no output schema. Minor omission: no note on behavior when the Guid does not resolve.

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?

With a single parameter and 100% schema description coverage, the schema already fully documents orderGuid including its Guid format pattern. The description only restates 'by Guid,' adding no syntax or format meaning beyond the schema, 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?

States a specific verb (Fetch), resource (purchase order), scope (single, by Guid), and names the returned contents (lines, supplier, totals). The word 'single' plus the required Guid makes it unambiguous versus the sibling unleashed_list_purchase_orders without 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?

Usage is implied by the phrase 'Fetch a single purchase order by Guid,' which tells the agent this is the right call when a Guid is known. However, it never states when NOT to use it or names unleashed_list_purchase_orders as the alternative for browsing, so guidance is implied rather than explicit.

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