search_customers_by_phone

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

With no annotations provided, the description must carry the full behavioral disclosure burden. It only states that it searches by phone number, without revealing whether it returns multiple customers, uses exact or partial matching, or any pagination. It adds little beyond what the tool name already implies.

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 a single sentence with zero redundant words. It front-loads the action and method, making it immediately scannable and efficient.

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 simple single-parameter search tool, the description is minimally adequate, but it lacks details about return behavior (e.g., multiple matches, ordering) and matching semantics (exact vs. fuzzy). Since there is no output schema, such context would help an agent use it correctly.

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%, so the parameter phoneNumber is already fully documented. The description's mention of 'by phone number' merely restates the schema. There is no added nuance about format, validation, or matching rules, which aligns with the baseline 3 for high coverage.

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 a specific action ('Search') on a specific resource ('customer') with a distinct method ('by phone number'). It inherently differentiates from siblings like search_customers_by_email and search_customers, making its purpose unambiguous.

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 implied: if you have a phone number, you use this tool. However, there is no explicit guidance on when to use it versus search_customers_by_email or search_customers, nor any exclusions. It meets the 'implied usage' criterion but lacks explicit routing.

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