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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds context the annotations cannot: the 48-hour retention window, the 'whether a tool used it already' flag, and the fact that the call costs no credits — all useful behavioral traits.

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 sentences, front-loaded with scope and followed by the trigger and the cost note. Dense and largely waste-free, though the returned-field enumeration is somewhat redundant given an output schema exists.

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?

For a two-parameter read tool with full annotation coverage and an output schema, the description supplies everything an agent needs: what it lists, the time window, when to invoke it, what to do with the returned id, and the cost. No material gap remains.

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 both limit and purpose are already documented in the schema, making 3 the baseline. The description's 'pass the id as recording_upload...' line refers to downstream tools' parameters rather than clarifying limit or purpose, so it adds little beyond the schema.

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 states a concrete resource (files the user handed over via upload page, links, attachments) with a precise temporal scope (last 48 hours) and enumerates returned fields (id, kind, name, size, length, age, used-by-tool). This implicitly separates it from asset-listing siblings like list_videos and list_images, but it never names or contrasts those siblings explicitly.

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 gives a clear trigger ('Call it after the user says they uploaded something') and a concrete follow-up (pass the id as recording_upload, photo_upload, driver_upload or music_upload), which tells the agent what to do next. It stops short of stating when not to use it or which sibling to prefer for generated assets.

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