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

Annotations already declare the mutation profile (readOnlyHint=false, idempotentHint=false, destructiveHint=false), so the bar is lower. The description usefully discloses that paths are read on the RDS host rather than the caller's machine, which is non-obvious and important, but says nothing about failure modes, overwrite behavior, or awaiting file-picker state.

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?

Three tightly packed sentences, front-loaded with the action and scope, then the host caveat, then the disambiguation. Zero filler; every clause earns its place.

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?

Covers purpose, the critical host-vs-local path distinction, and the sibling/device disambiguation for a simple 3-param tool with no output schema. Nothing an agent needs before calling it is missing.

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 100%, so all three parameters (paths, pageId, selector) are already documented in the schema, including the RDS-host constraint on paths. The description reinforces the RDS-host point but adds no syntax or format detail beyond the schema; baseline 3 applies.

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 (set files on a file input) scoped to the DESKTOP grid browser by pageId. It explicitly distinguishes itself from the device path and the nonexistent 'webpage_upload_file', so an agent can identify it 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?

Names the condition (desktop grid browser) and the alternative (ios_safari_set_input_files by udid) with an explicit 'NOT a device' exclusion. It also warns that no webpage_upload_file exists, closing off a plausible wrong guess.

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