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 value by naming the returned fields (id, name, address), which matters because there is no output schema. It does not say what happens on no-match or multiple-match, which is the main behavioral unknown for a phone lookup.

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?

Core purpose and return fields are front-loaded in one short sentence. The trailing 'GetCustomerInfoFromPhoneNumber' is an internal method name that adds no information for an agent and is mild noise.

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 one-parameter read-only lookup with no output schema, listing the returned fields covers the essential gap. Still missing is the not-found / ambiguous-match behavior an agent needs in order to interpret an empty or multi-result response.

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% and the single 'phone' parameter already documents format and length constraints (digits, e.g. 7132223333). The description adds no normalization or formatting guidance beyond 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?

A specific verb ('look up') plus resource ('a customer by phone number'), and it lists the returned fields (id, name, address). It implicitly distinguishes itself from ecourier_get_customer and ecourier_get_customer_by_code by keying on phone, though it never names those siblings explicitly.

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?

'useful when a caller rings in' gives one concrete scenario, which is more than nothing. But it never states when to prefer this over ecourier_get_customer or ecourier_get_customer_by_code, nor what to do when the caller has no phone or the number is unknown.

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