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 known. The description adds valuable behavior beyond annotations by specifying the ordering ('newest first') and the account scoping, which helps the agent understand what to expect.

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?

The description is a single, clear sentence that front-loads the main action and resource, with no filler or redundant information. It earns its place entirely.

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, read-only list tool with no parameters and an output schema present, the description fully covers what the tool does. It includes scope and ordering, which is complete for the tool's complexity.

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?

There are zero parameters, so the schema trivially covers everything. The description adds no parameter detail because none is needed. The baseline of 4 for zero-parameter tools applies here.

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 clearly states the verb 'List', the resource ('eSIM orders'), and the scope ('this account's'), plus the ordering ('newest first'). It effectively distinguishes from siblings like get_order_status (which implies a single order) and list_topup_options (which lists topup options).

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 description gives context that this lists all orders for the account, but it does not explicitly state when to use this versus alternatives like get_order_status. No exclusions or alternative tool mentions are provided, leaving the usage to be 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.