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

Annotations already declare readOnly and openWorld, and the description adds real context beyond them: logged-out access (no auth), routing through a residential proxy, and a pay-per-successful-call pricing model where failures are free. It stops short of disclosing failure modes, rate limits, or what happens with private/deleted reels.

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?

One dense paragraph that front-loads the returned payload before the input and operating details. The field enumeration is somewhat long but each item carries selection value; there is no filler.

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?

With an output schema present, the description needn't explain return values, yet it still summarizes them, and the single-parameter schema is fully covered. Gaps remain on error behavior and public-reel-only constraints, but nothing essential to calling it correctly is missing.

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 coverage is 100% for the single 'reel' parameter, and the description only restates what the schema already says ('Input a reel link or id'). This is the expected baseline when the schema does the work; no extra format or normalization detail is added.

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 names a specific resource (Facebook Reel details from the public reel page) and enumerates the exact fields returned (id, title, caption, duration, counts), so the agent knows precisely what it gets. It distinguishes itself from siblings through the platform name alone, since the sibling set is platform-keyed; there is no explicit contrast with social_facebook_posts or social_instagram_reel.

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?

It implies usage through 'logged-out view' and 'Input a reel link or id,' which tells the agent the input form and that only public reels are supported. But it never states when to prefer this over social_facebook_posts or social_instagram_reel, nor any exclusions such as private reels failing.

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