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

With no annotations, the description carries the full behavioral burden; it does disclose the response shape (owner name, carrier, source attribution) and hedges with 'if available', which usefully signals partial/empty results. It says nothing about coverage limits of OSINT sources, whether the call costs quota, latency, or what happens when the number is unknown.

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 two substantive sentences are front-loaded and waste-free, but the trailing '### Responses: **200**: Successful Response ... Content-Type: application/json' block is HTTP boilerplate that adds nothing for an agent and pads the definition.

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 two-parameter lookup with fully documented schema, the description covers purpose and output fields adequately. The gaps are the missing routing guidance against phone-related siblings and any statement about failure or no-result behavior, which matter more than usual because there is no output schema or annotation to fall back on.

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%, including the non-obvious detail that country_code excludes the '+' and that number omits the country code, so the schema already does the work. The description adds no format, normalization, or validation guidance beyond it, which is the expected baseline here.

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?

States a specific verb and resource ('Get information about a phone number using OSINT sources') and names the returned fields (owner name, carrier, source attribution). It does not differentiate itself from adjacent siblings such as get_documents_by_phone or search_leaks_by_phone, which look up related data by the same identifier, so an agent must infer the boundary.

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?

No when-to-use or when-not-to-use guidance is given, and no alternative is named. Given siblings that also accept phone numbers, an agent gets no signal about whether this is the profile-lookup entry point versus a document/leak search, leaving selection to guesswork.

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