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

Annotations only declare the generic mutation profile (readOnlyHint false, not idempotent, not destructive). The description adds genuinely new behavioral facts: the created page is private, it expires after 7 days, and the flow is asynchronous via a user confirmation step. None of that is derivable from annotations or the empty schema.

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 purpose, then trigger conditions, then the workflow, then the expiry constraint. Every sentence carries actionable information and none restates the title or the schema.

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?

There is no output schema, so the description must explain what comes back — and it does, specifying upload_page, upload_id, and the eventual photo_url from upload_photo. Combined with the 7-day expiry and the private-page nature, an agent has everything needed to run the flow 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?

The tool takes zero parameters and schema coverage is 100%, so the baseline is 4. The description goes further by naming the two opaque values that flow through the workflow (upload_page to the user, upload_id back into upload_photo), which is useful even though it concerns outputs rather than 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?

The description states a concrete verb and deliverable ('Create a private web page where the user can upload the poster photo') and immediately contrasts it with the sibling tool it is not ('whenever you can't pass the user's photo to upload_photo yourself'). An agent can distinguish this from upload_photo and get_poster_form without opening a 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 explicit trigger conditions (no link, user wants to pick from device, attached photo can't be forwarded) and names the alternative path (call upload_photo yourself when you can pass the photo). It also prescribes the follow-up workflow: hand the user upload_page, wait, then call upload_photo with upload_id.

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