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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower; the description still adds real value by disclosing the returned inventory (variants, status, preview, finished videoUrl) and the cost trait ("Free" = no credits consumed). It stops short of saying what happens on an unknown campaignId or whether variants can be mid-render.

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?

One dense, front-loaded sentence with no filler; the resource comes first and the return contents follow. Minor awkwardness in the parenthetical "(download)" and the unexplained "Silent UGC" framing.

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 one-parameter read with no output schema, the description usefully enumerates the return payload and cost, which is the main thing an agent needs. The remaining gap is the identifier's provenance/format, which neither schema nor description covers.

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?

The single parameter campaignId has 0% schema description coverage, and the description supplies nothing: no format, no note that the ID comes from ugc_create_campaign, no error semantics. The description does not compensate for the schema gap.

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?

Specific verb+resource ("Read a Silent UGC campaign") with an enumeration of what the reading returns: character, recording, hooks, variants, status, preview, videoUrl. An agent can distinguish it from ugc_create_campaign or ugc_render_batch by the verb alone, though the description never explicitly names an alternative.

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?

No when-to-use / when-not-to-use guidance and no pointer to the sibling that creates the campaign being read (ugc_create_campaign) or how it relates to ugc_preview. The only usage-adjacent signal is the trailing "Free."

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