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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered; the description then adds genuinely new behavior: a hard result cap of five, the word-containment matching rule, the exact fields returned, and an explicit privacy boundary (no contact details, tax id or address). That disclosure of what is deliberately withheld is exactly the kind of context annotations cannot carry.

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 sentences, front-loaded with the trigger condition, then the return contract and the exclusion. There is no filler and every clause carries information the agent needs.

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?

With an output schema present, the description need not enumerate return fields, yet it still summarizes them and states the cap and the privacy exclusions. Combined with full schema coverage and rich annotations, nothing needed to invoke this correctly is missing.

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 search parameter already documents the word-containment, order-insensitive, accent-insensitive matching, so the description's phrase "contains every word searched" largely restates the schema. It adds the five-result cap, which is a result behavior rather than parameter meaning, 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?

The description opens with a specific verb and resource ("find a customer... you need that customer's id") and immediately bounds the scope ("Not for listing every customer"), which separates it from list-style siblings and from update_customer. An agent can tell what this returns without opening the schema.

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?

It gives an explicit trigger condition ("when someone names a customer to update and you need that customer's id") and an explicit exclusion ("Not for listing every customer"). The only gap is that no sibling is named as the alternative for the listing case, so the agent must infer it from the tool list.

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