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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds useful content-level context by enumerating typical fee components (base rate, fuel, waiting time), which helps interpret the payload in the absence of an output schema, but says nothing about completeness, pagination, or whether zero-fee orders return an empty list.

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 compact, front-loaded sentence that leads with the returned resource and ends with the lookup key. The trailing 'GetOrderFees.' duplicates the name and title and earns no space.

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 rich annotations and no output schema, the description says enough to call it correctly and to know what comes back. Only the sibling distinction against ecourier_get_invoice_fees is left unaddressed.

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% and the single parameter is fully documented, including its provenance from ecourier_get_order. The description's 'by internal order id' merely restates the schema, 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?

Names the specific resource (fee lines of one order) and its scope (a single order, addressed by internal order id), with concrete examples of what a fee line contains. It is clear on its own, but it never acknowledges the closest sibling, ecourier_get_invoice_fees, so an agent must infer the difference between order-level and invoice-level fees.

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 states what is retrieved but gives no explicit when-to-use condition, no exclusion, and no named alternative among the many fee/order siblings. The only routing hint, that the id comes from ecourier_get_order, lives in the schema's parameter description rather than in the tool description.

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