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

Annotations already declare readOnlyHint=true and openWorldHint=true, which tells the agent this is a safe, non-mutating operation that can handle unknown inputs. The description adds the fact that it works for both posts and Reels and that a URL is required—useful but not substantial beyond the annotations. It does not contradict the annotations, nor does it disclose additional behaviors like error handling or rate limits. Given the annotation coverage, a 3 is appropriate.

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?

A single, front-loaded sentence: 'Get the transcript for a Facebook post or Reel by URL.' Every word earns its place—verb, object, scope, and input method are all conveyed. There is zero redundancy or filler, making it extremely concise and easy to parse.

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, read-only tool with one parameter and no output schema, the description covers the essential information: what it retrieves (transcript), what it operates on (Facebook posts and Reels), and how to invoke it (providing a URL). The annotations cover safety (read-only) and flexibility (open-world). Nothing critical is missing for an agent to call this tool correctly, though it could optionally mention the transcript format or behavior when no transcript exists.

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 schema has 100% coverage for the single required 'url' parameter, with a clear description: 'Link to the Facebook post or reel whose transcript should be returned.' The tool description only repeats 'by URL,' adding no new meaning or format details. With the schema fully documenting the parameter, the baseline of 3 is correct.

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 verb ('Get') and a precise resource ('transcript for a Facebook post or Reel by URL'). It clearly indicates what the tool returns and distinguishes it from other platform-specific transcript tools in the sibling list (e.g., instagram_post_transcript_get, youtube_video_transcript_get) by its explicit Facebook scope. No ambiguity remains about the tool's function.

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 implies usage: when you have a Facebook post or Reel URL and need its transcript. However, it does not explicitly state when to use this tool over alternatives (e.g., facebook_post_get for post metadata) or when not to use it, such as if a transcript is unavailable. The guidance is minimal and relies on the tool name and context rather than explicit instructions.

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