nessie_get_customer

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

The annotations already provide readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the 'Read-only' sentence is mostly redundant. The description does add a useful behavioral cue that exactly one customer is returned, but it does not describe not-found behavior, error cases, or the response shape. There is no contradiction with the annotations.

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?

The description is appropriately short and front-loaded with the verb, resource, and lookup key. The only minor redundancy is 'Read-only,' which repeats an existing annotation, but it does not meaningfully bloat the description.

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 fetch with full schema coverage and safety annotations, the description is nearly complete for correct invocation. The main gap is that there is no output schema and the description does not explicitly state what happens for an unknown customer ID or the exact return shape; 'get one customer' covers most of the intent.

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 schema already documents customerId as an opaque string with minLength 1. The description's phrase 'opaque customer id' merely restates that schema detail and confirms the parameter is the lookup key; it adds no new format, default, or edge-case semantics.

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?

The description opens with a specific verb and resource: 'Get one Nessie customer by opaque customer id.' The singular 'one' and the ID-based lookup make it clear this is a single-resource fetch, and 'Read-only' distinguishes it from mutation tools. It is unambiguous against siblings like nessie_list_customers or nessie_get_account.

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?

The description implies the right usage — fetch one customer when you already have an opaque customerId — but it never explicitly states when to prefer this over nessie_list_customers or when not to use it. This is implied usage rather than stated guidance, and no alternatives are named.

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