upload_file

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

No annotations are provided, so the description carries the full burden, and it discloses genuinely useful traits: a per-call permission prompt and an atomic guarantee that missing paths are reported before anything is attached, so a picker is never left half-filled. It omits what a successful result looks like and what happens if permission is declined, but the disclosure is well above average for an unannotated tool.

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?

Four short sentences, front-loaded with the core action, followed by the permission caveat, the selector note, and the atomicity guarantee. Every sentence carries information; no filler or restated title.

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 values need not be described. Given that, the description covers the action, its permission gate, the selector nuance, and failure timing adequately; only the semantics of the reason and confirm parameters remain unexplained for a 4-parameter tool.

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 description coverage is 0%, so the description must compensate and it only partially does: it explains selector (the input[type=file], which may be hidden) and implies paths semantics via the pre-flight missing-path check. The 'reason' and 'confirm' parameters are never addressed, and only the vague mention of a permission request hints at confirm's role.

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 ('Attach one or more local files') and immediately differentiates itself from siblings like click, type_text, or set_editor by naming the target as a file picker. An agent can identify this as the file-upload tool without opening the 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?

Provides the context needed to invoke it: the target is the input[type=file] selector, hidden inputs are acceptable, and it asks for its own permission once per call. It does not name when not to use it or point to an alternative (e.g. ask_user_to_do), so it stops short of full routing guidance.

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