get_carrier_info

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It states what the tool does (lookup) and returns (carrier details with MCC/MNC codes), but it doesn't disclose critical traits like whether it's a read-only operation, rate limits, authentication needs, error handling, or data freshness. For a lookup tool with zero annotation coverage, this is a significant gap, though it's not misleading.

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 appropriately sized and front-loaded: the first sentence states the core purpose, followed by structured 'Args' and 'Returns' sections. Every sentence earns its place by providing essential information without redundancy. It's efficient and well-organized for a tool with one parameter.

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?

Given the tool's low complexity (one parameter) and the presence of an output schema (implied by 'Returns' section), the description is mostly complete. It covers purpose, parameter semantics, and return values. However, with no annotations, it lacks behavioral context like safety or performance traits. For a simple lookup tool, this is adequate but could be improved with more disclosure.

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 has 0% description coverage, so the description must compensate. It adds meaning by specifying that the 'ip' parameter is an 'IP address to lookup', which clarifies its purpose beyond the schema's generic 'string' type. However, it doesn't provide format details (e.g., IPv4 vs. IPv6) or validation rules. With one parameter and no schema descriptions, this is good but not exhaustive.

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 tool's purpose: 'Get mobile carrier information for an IP address.' It specifies the verb ('Get') and resource ('mobile carrier information'), and distinguishes it from siblings by focusing on carrier details rather than general IP info, location, or other lookups. However, it doesn't explicitly differentiate from all siblings (e.g., 'get_ip_info' might overlap in scope), so it's not a perfect 5.

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 context by specifying 'for an IP address' and mentioning mobile carrier details, suggesting it's for IP-to-carrier mapping. However, it doesn't explicitly state when to use this tool versus alternatives like 'get_ip_info' or 'get_ip_location', nor does it provide exclusions or prerequisites. The context is clear but lacks explicit guidance on sibling differentiation.

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