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

Adds substantial traits beyond readOnlyHint/openWorldHint: reads the reels tab first, paginates ten at a time via pagination.cursor, falls back to the video grid (~20 entries with titles, views, durations) with no cursor, returns videos instead of erroring, and costs 1 credit. This is exactly the operational context annotations cannot carry.

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?

Front-loaded with the core purpose, then pagination/fallback behavior, then item-keying and cost. Dense but every sentence carries information; the fallback sentence is long but earns its place.

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 no output schema, the description usefully sketches the return shape (video-id-keyed items, titles, view counts, durations, pagination.cursor) and the fallback path. Only cache_max_age semantics are left unexplained, a minor gap.

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 67%; url and cursor are already documented in the schema, and the description only restates cursor behavior. cache_max_age has no description in either place, so no compensation for the gap. Baseline 3 is appropriate.

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: public videos and reels from a Facebook Page. This is clearly distinguishable from siblings like facebook_pagePosts or facebook_pageAds without opening the schema.

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 gives context for when this applies (fetching a Page's reels/videos) and even pipeline guidance — items can be passed to /v1/facebook/post or /v1/facebook/post-transcript. It does not explicitly name when to prefer a sibling instead (e.g., pagePosts for text posts), which keeps it from a 5.

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