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

No annotations are provided, so the description carries the full burden. It only discloses that the tool works 'offline', which is a minor behavioral trait. It does not state what the tool does with the input, whether it returns a single result or multiple, or any limitations or error conditions. For a tool with zero annotation coverage, this is insufficient.

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 very short, but it is not structured for quick comprehension. It is a fragment rather than a clear sentence, and it front-loads a title rather than actionable information. While it is concise, it sacrifices necessary detail.

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?

An output schema exists, but the description does not explain what the tool returns or how the output corresponds to the input. Given the tool's simplicity, it might be usable with just the schema, but the description leaves too much ambiguity about input semantics and expected output.

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 one parameter 'q' with 0% description coverage. The description does not explain what 'q' represents (country name, calling code, trunk prefix, etc.) or its format. The agent cannot determine how to construct a valid query without additional context.

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 is a noun phrase ('Calling Code: Country, trunk & intl dialing prefixes (offline)') rather than a sentence with a verb. It implies the tool provides calling code information, but it does not specify the action (lookup, format, validation) or the input/output relationship. It does not distinguish itself from sibling phone-related tools like phone, phonefmt, or phonepivot.

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?

There is no guidance on when to use this tool versus alternatives. No mention of typical use cases, prerequisites, or exclusions. The agent is left to guess whether to use this or the many other phone/calling-code tools.

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