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

With no annotations, the description carries the full burden for disclosing behavior. It only says 'Retrieves', which implies a read operation, but does not mention idempotency, error handling, authentication requirements, or any side effects. The additional billing and group metadata do not disclose behavioral traits.

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 essential description is one concise sentence that front-loads the primary action. However, it includes metadata ('Group: Facebook-Profile' and 'Billing per call') that is not crucial for tool selection, adding slight noise, but it remains compact and clear.

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 such a simple tool, the description is minimal but lacks critical context: it does not specify the return value format (e.g., numeric ID, string), how errors are handled, or any edge cases. With no output schema and no annotations, the description should clarify the expected output to be complete.

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 provides 100% coverage for the single parameter 'url' with a description and example. The description just repeats 'Facebook profile URL' without adding extra meaning like format expectations, validation rules, or behavior on invalid URLs. Baseline of 3 is appropriate since the schema already documents the parameter.

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 retrieves the profile ID for a Facebook profile URL, specifying the exact resource (profile ID) and distinguishing it from sibling tools that fetch other profile aspects (about, details, photos, reels).

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 guidance is provided on when to use this tool versus alternatives. It does not mention prerequisites, context, or mention that it might be a first step before using other profile tools. The description only states the function without any usage context.

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