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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, destructiveHint=false, openWorldHint=false), so the description's job is to add scope. It does: the data is scoped to the calling API key, limited to the current month, and covers two specific metrics (calls and video downloads), which no annotation conveys. It stops short of saying whether values are counts, limits, or percentages, and says nothing about caching or quota-window boundaries.

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 short sentence, zero filler, with the scope (this API key) and the time window (this month) front-loaded. Nothing could be removed without losing scope information.

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?

With no output schema, the description must carry the return-value burden, and it does name the three things returned: plan, call usage, and video-download usage. Given a zero-parameter, low-complexity tool this is close to sufficient, though it leaves the shape of those values (raw counts vs. limits vs. remaining quota) unstated.

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 tool takes zero parameters, so there is no schema semantics for the description to compensate for; baseline for a no-param tool is 4. The description appropriately devotes no words to 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 names the exact resource (this API key's plan and month-to-date call and video-download consumption), which is specific enough to distinguish it from every sibling (get_collection, get_trending, get_green_screen, etc.). It omits an explicit retrieval verb — 'Get' only appears in the name/title — so it reads as a return-value sketch rather than a stated action, which keeps it out of the top band.

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?

There is no explicit when-to-use or when-not-to-use statement and no alternative tool is named. The scope words 'this month's calls and video downloads' do imply the natural use case (checking quota/plan before or after heavy usage), but the agent must infer that rather than being told.

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