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

Annotations already cover readOnly/destructive/openWorld, so the bar is lower. The description adds meaningful behavioral context beyond that: the link is 'short-lived,' it must be handed to the user, the agent should wait for confirmation, and then it should verify via autoposter_list_media before attaching. This is genuinely useful operational detail.

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?

Three sentences, front-loaded with the core action before usage guidance and the follow-up workflow. Every sentence earns its place. The final sentence is dense but functional rather than wasteful.

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?

An output schema exists, so return-value details are not required. With no parameters and annotations covering the safety profile, the definition supplies what's needed to invoke and sequence the call. The main remaining gap is explicit differentiation from the similarly named get_media_upload_url sibling.

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 tool takes zero parameters (empty object, 100% coverage), so the baseline is 4. There are no parameter semantics for the description to clarify, and it adds nothing that could mislead about inputs.

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: 'Creates a short-lived link where the user can upload images ... into the Auto Poster media library.' This is clear and non-tautological. However, it does not distinguish itself from the close siblings autoposter_get_media_upload_url and autoposter_upload_media, so an agent must still infer which is the right one.

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?

Gives a precise trigger condition: use it 'when the user wants to attach an image that exists only in the chat or on their device (no public URL) and your client cannot send file contents.' It even prescribes the follow-up workflow. It stops short of explicitly naming the alternative tools (autoposter_upload_media / autoposter_get_media_upload_url) to contrast against.

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