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

Annotations already declare destructiveHint=true, openWorldHint=true and non-idempotent, so the safety profile is covered. The description adds genuinely new behavior: the 10-file and 20 MB caps, the two accepted file-reference shapes, and that it returns the page state afterward ("the elements and text in view, with the same numbers"). It does not say what happens on partial failure or oversized files, which is the remaining gap.

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 action leads, followed by accepted file shapes, limits, and return behavior — a sensible order with no filler sentences. The dense colon/semicolon packing makes it read as one long clause chain, though nothing is strictly wasted.

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 usefully describes the return value (page elements and text with consistent numbering) and supplies size/count limits, which is most of what an agent needs for a browser file-input tool. Missing pieces are error handling and any prerequisite about the file input being present on the current page.

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, but the description adds meaning the schema cannot express: the 20 MB per-file limit (only maxItems=10 appears in the schema) and the oral-form distinction between a public `url` and a Cotlet `file_id`. The `element` numbering hint is already in the schema, so it is repeated rather than added.

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 uses a concrete verb and target ("Puts files into file field or upload button `element`"), which tells an agent exactly which page control is being acted on. It does not name the sibling `cotlet_upload_file`, which is the natural confusion point since the `file_id` form implies that tool runs first; only the phrase "a file uploaded to Cotlet" hints at the ordering.

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?

Usage is implied rather than stated: files must already exist as a public URL or a prior Cotlet upload, and the `element` must come from the last read/step answer. There is no explicit when-to-use / when-not-to-use guidance and no pointer to `cotlet_upload_file` for the upload-to-Cotlet step or to `cotlet_browser_read` for refreshing element numbers.

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