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

Annotations already flag destructive, open-world, non-idempotent behavior, and the description adds real value on top: accepted file source shapes, the 10-file / 20 MB limits, the returned URL and title, and the per-minute credit cost with the 3-minute idle timeout. It does not say what happens on partial failure or whether existing field content is replaced, which keeps it short of a 5.

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?

Two dense sentences, purpose and input shape front-loaded, with cost/session policy last. Every clause carries information, though the credit-and-timeout clause sits somewhat awkwardly in a tool-purpose description.

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?

With no output schema, the description correctly states the return value (URL and title), and it covers input forms and limits. The main gap is the missing reference to how a browser session must already exist and how this differs from cotlet_upload_file.

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 the baseline is 3. The description restates the url/file_id alternatives and the element-number meaning that the schema already documents, adding limits (10 files, 20 MB) but no genuinely new semantics such as how the element list is obtained or what happens if element is not a file input.

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 gives a specific verb and resource ('puts files into a file field of the current page in the user's browser'), plus the targeting mechanism (element number). It distinguishes itself from generic upload behavior by naming the browser/session context, but it never contrasts itself with the sibling cotlet_upload_file, which an agent could easily confuse it with.

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 browser-session framing and the note that the session ends on close or 3 minutes after the last call imply when this tool fits, but there is no explicit 'use this instead of cotlet_upload_file when...' guidance, and no prerequisites (e.g. needing an open browser session from cotlet_browser_open/connect) are stated.

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