upload

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

The only annotation is openWorldHint=true, so the description carries most of the burden and does so well: it discloses that chooser interception suppresses the native dialog, that paths must resolve inside enumerated allowed roots, and that dot-files are refused unless a flag is set. It does not describe failure behavior (e.g., what happens when a path is rejected) or whether uploads are synchronous, which keeps it from 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?

Single densely packed paragraph with the action front-loaded and no filler sentences. The parenthetical notes earn their place by explaining observable behavior, though the sentence is long enough that an agent must parse several constraints at once.

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 and only three parameters, the description covers the operationally important ground: target resolution modes, path sandboxing, and hidden-file policy. It omits what the tool returns or reports on success/partial failure, which is a modest gap given there is no output schema to fall back on.

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 67% and the description compensates for the undocumented core parameter: it explains what kinds of target are acceptable and — more importantly — the behavioral difference between them, going beyond the schema's enumeration of ref/point/selector forms. It also qualifies the paths parameter with root restrictions and hidden-file rules. The tab parameter is left entirely to its schema description, so not a 5.

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 opens with a specific verb and resource ("Upload files") and immediately distinguishes the two invocation mechanisms: a direct input[type=file] versus an element that opens a chooser. That is enough for an agent to tell it apart from siblings like type, fill_form, or click without opening any 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 clearly explains the two contexts in which the tool applies (direct file input vs. chooser-opening element) and notes that no native dialog will appear in the second case, which shapes how the agent should sequence calls. It does not name an alternative tool or explicitly state when not to use it, so it stops short of a 5.

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