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

Annotations already declare readOnlyHint=true, so the safety profile is covered by structured data. The description adds the underlying REST endpoint and a summary of returned fields, but says nothing about auth requirements, error behavior when the id is unknown, or rate limits.

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 sentence plus an endpoint reference, front-loaded with the action and resource before the field list. Nothing is redundant or padded.

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?

There is no output schema, and the description partially compensates by naming address, domain, phone, and notes as the payload. For a simple one-parameter getter this is nearly sufficient; a fuller field list or an error-case note would round it out.

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 parameter is documented in-schema as the CustomerID with a positivity constraint, so the description carries little extra burden. 'By id' reinforces the schema but adds no format or sourcing detail beyond it.

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 ('Fetch a single customer by id') and enumerates the returned fields, so the intent is unambiguous. It does not name the sibling atera_list_customers, relying on 'a single customer' to imply the distinction.

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: 'by id' signals that the agent needs a customer_id in hand, but the description never says when to prefer this over atera_list_customers or a search tool, nor any prerequisites.

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