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

Annotations already declare readOnlyHint=true, destructiveHint=false, openWorldHint=false, so safety is covered structurally. The description adds genuinely new behavioral context beyond them: "Costs no credits" tells the agent this call is free to invoke freely, and it discloses that the response embeds three suggested next actions with their target tool. It stops short of describing pagination or latency, but for a read-only aggregate that is minor.

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?

It is front-loaded with the imperative "Start here" and then a single dense sentence enumerating the payload, followed by the usage line and a cost note. Every sentence earns its place, though the middle enumeration is long and could be tightened without loss.

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?

Given the low complexity (no params, read-only, closed-world, and an existing output schema), the description supplies everything an agent needs: what it returns, when to call it, that it is free, and that it points to next tools. Return-value details are already carried by the output schema, so nothing required is absent.

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 per the rubric the baseline is 4 and there are no parameter semantics for the description to clarify. Nothing is missing or misleading here.

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 gives a concrete, specific function — a single session-start call that aggregates credits/prices, plan limits, entity counts (influencers, looks, clips, videos, uploads), the app on file, latest items, and three suggested next tools. This implicitly and effectively distinguishes it from the granular siblings (get_credits, list_clips, list_videos, get_content_plan), which return only one slice each. An agent can tell what this does without opening any 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?

It states explicit trigger conditions: "Use it at the start of a session and whenever the user asks what to do next." That is clear context for invocation. It does not name a competing alternative or an explicit when-not (e.g., "instead of get_credits"), so it stops just short of full routing guidance.

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