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

Annotations already cover readOnly, openWorld and non-destructive, so the bar is lower; the description still adds two things they do not: the required auth scope ('Needs read_customers') and the exact-match semantics of the lookup keys. It omits return shape and result-count behavior, but the pagination contract is carried by the schema.

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?

Three short sentences, front-loaded with the action and the key constraint, with no filler. The endpoint path is marginally useful but adds little for an agent that already has the tool; minor redundancy against the schema's own field descriptions.

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?

Five optional params, no enums, no output schema, and annotations carrying the safety profile. The description supplies the one thing structured data lacks (at-least-one-key rule) plus auth scope, leaving nothing an agent needs before calling it.

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 baseline would be 3, but the description adds a constraint the schema does not express at all: no parameter is marked required, yet the description says to pass at least one of email/phone/code. That is genuine semantic value beyond the structured fields.

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 verb and resource ('Find customers') and the three exact-match keys it accepts (email, phone, code), which distinguishes it from easystore_list_customers. It never names the sibling it replaces, so an agent must infer the search-vs-list split from the words 'exact' and 'Find'.

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?

'Pass at least one' gives a real invocation constraint and 'exact' implies this is not a fuzzy or listing endpoint, so usage is inferable. But there is no explicit statement of when to prefer it over easystore_get_customer (single-record lookup) or easystore_list_customers (browse), which are the two obvious alternatives in the sibling set.

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