Preview post pictures

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

The description adds substantial context beyond annotations: link validity of one hour, per-channel format/shape/mode details, what errors communicates, side effects of generating missing pictures, preview-limit and storage impact, and the read-only key case. These disclosures are important because the tool can trigger picture creation even though the post itself is unchanged.

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 and front-loads the key point that the post is unchanged, then covers outputs, side effects, and next steps. It is longer than typical but almost every sentence adds actionable information; it could be slightly tighter or better structured but is not bloated.

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 preview tool with no output schema and minimal annotations, the description provides the missing behavioral and output context: per-channel picture details, link expiry, error semantics, rendering guidance, side effects, and alternative-key behavior. An agent has enough information to call and use the tool correctly.

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?

There is only one parameter, postId, but schema description coverage is 0% and the description never explicitly explains the parameter's meaning or accepted format. The purpose and context imply it is the post being previewed, so it is usable, but the description misses an opportunity to compensate for the bare schema.

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 makes clear this is a preview tool that returns the exact pictures per channel without changing the post. It also explicitly distinguishes its role from related siblings like postfjord_schedule_post, postfjord_publish_now, and postfjord_update_post.

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 states exactly when to call it (before scheduling or publishing), what to show the user, how to handle bad crops, and when to re-preview after using postfjord_update_post. It also explains read-only key behavior, giving a complete usage contract.

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