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

Annotations already declare readOnlyHint=true, openWorldHint=true and destructiveHint=false, so the safety profile is covered. The description adds that the response includes lines, state and fulfilment, but says nothing about behavior on an unknown id, permissions, or pagination/expansion options.

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 short sentences with the returned payload front-loaded and no filler. The bare REST endpoint is marginal value for an agent but is short enough not to hurt.

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 single-parameter read tool with full annotations, the description covers what is returned (header, lines, state, fulfilment), which is the main thing missing from structured fields since there is no output schema. Only failure/permission behavior is absent.

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?

Only one parameter and schema coverage is 100%, so the schema already documents purchase_order_id fully. The {id} path template hints at where the id originates, but no additional format or sourcing guidance is added 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 resource (one purchase order) and enumerates the returned payload (lines, state, fulfilment), which tells an agent what it gets rather than just restating the title. It does not explicitly name the list-vs-get alternative, but the get_/list_ sibling naming makes the distinction 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: the singular resource and the REST path suggest 'call this when you already have an id and need the full record', while list_* siblings cover discovery. No explicit when-to-use/when-not or prerequisites are stated.

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