get_phone_number

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

With no annotations provided, the description carries the burden of behavioral disclosure. It mentions the return type as a Dict containing Number Object(s) with record_type 'phone_number', but does not explicitly state that this is a read-only operation, nor does it cover error conditions or required permissions.

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 compact and well-structured: one line for the action, one for the argument, and one for the return value. There is no fluff or redundant information, and each sentence serves a clear purpose.

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 tool with one parameter and no output schema, the description covers the essential information: action, parameter, and high-level return shape. However, it could be more explicit about the cardinality (single object vs multiple) and the structure of the Number Object, but it is adequate for basic usage given the simplicity.

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?

The input schema already fully describes the 'id' parameter as 'Phone number ID as string' with 100% coverage, and the description repeats the same text without adding any new meaning, formatting details, or examples. The baseline score of 3 applies because the schema does the heavy lifting.

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 'Get a phone number by ID', which is a specific verb (get) with a resource (phone number) and a parameter (ID). This distinguishes it from sibling tools like list_phone_numbers and update_phone_number.

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 usage when a phone number ID is available and a single record is needed. However, it does not explicitly mention alternatives like list_phone_numbers for browsing or update_phone_number for modifications, leaving the when-to-use guidance implicit.

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