Cross-Post to Facebook Page & Instagram

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

Annotations already indicate this is a write operation (readOnlyHint=false) and non-destructive. The description adds valuable behavioral details: it uses Promise.allSettled to handle partial failure, and for text-only content, only Facebook receives a post (Instagram doesn't support text-only).

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 well-structured with bullet points and clear sections. It is front-loaded with the main purpose, and every sentence adds value. No unnecessary information.

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 tool has 6 parameters, 3 required, and no output schema, the description adequately explains the return behavior (results from both platforms with success/failure) and the prerequisite. It could mention error handling for invalid URLs or auth issues, but it is sufficient for 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 baseline is 3. The description adds significant extra semantics by explaining how parameters interact: if image_url is provided, both platforms get photo posts; if video_url, both get Reels; if text only, only Facebook gets a text post. This goes beyond the schema descriptions.

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 tool's name and title clearly indicate cross-posting to Facebook and Instagram. The description explicitly states 'Publishes the same content to both a Facebook Page and Instagram simultaneously.' This distinguishes it from siblings like meta_create_photo_post and meta_publish_instagram_photo, which are single-platform.

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 provides a clear prerequisite: 'meta_list_pages must be called first to load page tokens.' It also explains the logic for different media types (image, video, text-only). While it doesn't explicitly state when not to use it, the context is clear enough for an agent to decide.

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