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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds real value beyond that by enumerating the returned fields and citing the underlying REST endpoint (GET /customers/<CUSTOMER_ID>.api), which tells the agent the response is a single object, not a collection. Missing are error behaviour for unknown ids and any note on expandable/nested sub-resources (e.g. whether addresses are inline or require list_customer_addresses).

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 short fragments, front-loaded with the cardinality plus resource and followed by the payload summary; every token carries information and there is no preamble or repetition.

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-param read tool with annotations covering safety and no output schema, the field enumeration in the description effectively substitutes for a return-value spec. It would be complete at 5 if it noted the not-found behaviour or clarified whether addresses/custom fields are inline versus requiring separate calls.

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 param already documents both the type (integer or numeric string) and its provenance ("from ezrentout_list_customers"). The description's "by id" adds nothing beyond that, so the schema is doing all the work – the baseline 3.

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?

"One customer by id" is a specific verb+resource with an explicit cardinality, which separates it from the many list_* siblings without naming them. It also enumerates the returned fields (name, email, phone, addresses, status, custom fields), so an agent knows exactly what it gets back. It stops short of naming the alternative (ezrentout_list_customers / search_member_by_email) 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?

Usage is only implied: you need a customer_id, and the sibling list of tools makes clear this is the single-record counterpart to ezrentout_list_customers. There is no explicit "use this when you already have an id, use list_customers when you don't" statement, and no mention of what happens when the id is unknown.

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