List Reels

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

Beyond the readOnlyHint, openWorldHint, idempotentHint, and destructiveHint annotations, the description adds genuinely valuable behavioral context: Reel items are video nodes rather than post nodes, the field set is best-effort and may need `fields` overrides, and each item id is a VIDEO id suitable only for facebook_reel_insights. This materially changes how an agent interprets results and downstream calls.

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 dense but every sentence earns its place: it front-loads the core purpose, then covers sibling differentiation, pagination, item shape, field-set caveats, and id semantics without repetition. Despite its length, it remains tightly scoped and immediately useful.

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 absence of an output schema, the description compensates well by describing the return items as video nodes with their notable fields, and by clarifying the cursor flow. It also covers the main cross-tool pitfalls (empty post listings, wrong insights tool). For a read-only listing tool with four optional parameters, this is complete enough for correct selection and invocation.

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%, so the schema already documents all four parameters clearly. The description adds extra meaning by explaining that `after` follows the same cursor pattern as post listings, that `fields` can compensate for rejected default fields, and that the returned id is a video-specific identifier. This goes beyond the baseline but is not exhaustive for every 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 states a specific action ('List a Page's Reels'), names the exact Graph edge (/video_reels), and explicitly distinguishes this from facebook_list_posts by noting Reels never appear there. This gives an agent a precise, unambiguous understanding of what the tool does and how it differs from sibling tools.

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 gives explicit when-to-use guidance: use this whenever Reels matter, and never infer from an empty post listing that a Page has no video content. It also names the correct sibling for insights (facebook_reel_insights) and the incorrect one (facebook_post_insights), leaving no ambiguity about alternatives.

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