customers__get_customer_by_phone

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

The description goes beyond the annotations by disclosing that the tool is a wrapper with no own throttling but consumes the underlying API's quota, and advises caching the result in the dialog. This is valuable operational context that annotations (readOnlyHint=true, destructiveHint=false) do not cover. It does not describe return behavior, but given the safety annotations are already present, this extra context earns a high score.

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 concise: a single sentence for purpose plus a second sentence for behavioral advice. It is front-loaded with the core action and adds only essential context. No unnecessary fluff. This is efficient and well-structured.

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 tool with only two parameters and no output schema, the description covers the purpose and some behavioral nuances but omits parameter semantics (especially organization_id) and does not clarify what exactly is returned (though this is implied by the name). The caching advice is useful, but the missing parameter explanation makes it incomplete for a fully informed call.

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 0%, so the description must compensate for parameter meaning. It only mentions the phone number in the purpose, but does not explain the organization_id parameter, its format, or why it is required. The schema itself provides no descriptions, leaving the agent without adequate understanding of the second parameter. This is a significant gap.

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 clearly states the action and resource: 'Get customer by phone number'. It is specific and distinct from sibling tools like get_customer_by_id, get_customer_by_email, and get_customer_by_card_track. However, it does not explicitly mention the organization scoping (which appears in the parameters), so it is slightly less than perfectly clear.

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 provides no guidance on when to use this tool versus the many sibling customer lookup tools. It does not mention that this is the appropriate choice when only a phone number is available, nor does it explain alternatives or exclusions. The agent must infer usage from the name alone.

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