Get customer

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

Annotations already declare readOnlyHint=true, so the safety profile is covered. Beyond that the description adds nothing: it does not say what happens when the id is unknown (null vs error), whether the lookup is cached, or any permission requirement. For a tool whose annotations already carry the read-only signal, the description contributes essentially no extra behavioral context.

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 short, front-loaded sentence with a verb, a resource, and the lookup qualifier. There is no filler and nothing that would need to be moved earlier.

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?

This is a simple single-parameter read with an output schema, so much of the burden is already carried by structured fields. Still, a complete definition would say how a missing or invalid id is surfaced, which matters for an agent deciding whether to call this or list_customers.

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 description coverage is 100%: the single customerId parameter is documented in the schema with its origin ("Customer id from list_customers"), including type and bounds. The description adds no format, range, or sourcing detail beyond that, so the 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?

States a specific verb and resource ("Get one customer") and the lookup key ("by id"), which implicitly distinguishes it from the sibling list_customers. It stops short of explicitly naming the sibling the way a 5 would.

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 phrase "by id" implies you must already have a customer id, and the sibling name list_customers is only hinted at via the schema's "Customer id from list_customers". There is no explicit when-to-use-this-vs-alternatives guidance or mention of what to do without an id.

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