upload_file

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

With no annotations, the description carries full burden. It discloses Chromium dependency, debugging port requirement, and behavior when file input is dynamically inserted. Lacks details on error cases or file size limits, but sufficiently describes operational context.

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 description is structured with multiple informative sentences, each adding value. However, it could be slightly more concise without losing clarity (e.g., the Chromium startup details might be extraneous). The cross-reference to click() is efficient.

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?

Despite good purpose and usage guidance, the description lacks complete parameter explanations for all 5 parameters (e.g., instance, observe, settle_ms) and does not describe any output or success/failure behavior. Without an output schema, this is a notable gap.

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 description must compensate. It explains 'selector' (targets main page, default = first file input) and references observe/settle_ms to click(), but does not explain 'filepath' (obvious) or 'instance' (unclear meaning). Incomplete coverage of 5 parameters.

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 clearly states the tool's action: 'Attach a local file to a page's <input type=file> via Chrome DevTools Protocol'. It specifies the resource (file input) and the verb (upload), and distinguishes from siblings by noting native apps use open_file().

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?

Explicitly says 'use this for ALL browser uploads' and warns against clicking upload buttons due to renderer hang. Provides conditional guidance (click first if input is inserted dynamically) and contrasts with native apps (open_file()). References sibling click() for similar parameters.

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