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

Annotations already cover the safety profile (readOnlyHint, destructiveHint=false, openWorldHint), so the description earns credit for adding real behavior: the meaning of the N/A/X status codes and the explicit exclusion 'Signature images are not returned.' It stops short of saying what happens on zero or multiple matches, which matters given no required parameters.

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 sentences, front-loaded with what is returned and then how to address it, with no filler. The field enumeration is long but each item is a distinct return-value category the agent cannot get from an output schema, so it earns its 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?

With no output schema, the description carries the return-value burden and does so thoroughly, including the signature-image exclusion. The remaining gap is error/disambiguation behavior (no-match, multiple-match, or what happens if zero selectors are supplied despite the 'exactly one' instruction).

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 coverage is 100% so the baseline is 3, but the description adds a constraint the schema does not encode: exactly one of order_number, order_id, auth or reference (the schema marks nothing required and declares no oneOf). It also explains that customer_code is used to narrow a reference lookup, which is more than the schema's 'useful together with reference.'

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?

Specific verb+resource ('One delivery order') followed by an explicit enumeration of the payload: status codes with meanings, customer, stops with pickup/delivery times and POD names, pieces, jobs, drivers, fees, events and notifications. The payload listing implicitly separates it from narrow siblings like ecourier_get_order_fees, which only returns a subset.

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 'give exactly one of...' selector clause, which tells the agent how to call it but not when to prefer it over ecourier_get_order_fees or ecourier_get_manifest. No when-not-to-use or explicit alternative routing is provided.

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