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

Beyond the annotations it discloses the interactive-card behavior, per-file upload status feedback, and that photos land in the project as images — real context an agent can't get from the schema. It is weaker on the destructiveHint=true dimension: it never spells out what gets destroyed or discarded, leaving the 'replace' semantics partially implicit.

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 structure is front-loaded and information-dense: capability first, then exclusions with alternatives, then the phone/export edge case. It is a single dense paragraph with long clauses, slightly harder to scan than a bulleted breakdown, but no sentence is filler.

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 three-parameter interactive tool with no output schema, the description covers what happens, what the card reports, and the one non-obvious workflow (phone copies replaced before export). It does not say what the call returns or how it behaves if the person cancels the card, which is the remaining 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 coverage is 100%, so the parameters are already documented; the description still adds value by framing `replace` as part of a gated workflow (ask the person first, then call once per clip) rather than a bare media id. `goal` is not discussed in the description, but the schema fully covers it.

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 specific verb and resource ('Opens Cardboard's upload card in the chat') and names the exact file kinds accepted, so an agent knows precisely what it does. It also distinguishes itself from the sibling add_media by scope ('video, audio and photos already attached to the chat go in with add_media instead').

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 explicit when-to-use (device-local footage/photos must reach Cardboard), explicit when-not-to-use (documents like briefs, scripts, shot lists; chat-attached media), and names the alternative tool for each exclusion. The phone-original workflow ties invocation to a precondition ('before export_video, ask whether to replace those clips').

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