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

Annotations already establish this as a safe, idempotent, closed read; the description goes well beyond them by documenting downstream error semantics (402 plan_required, 402 storage_full), that monthly credits reset while top-ups never expire, and that deleting videos or archiving songs frees space immediately. That is actionable behavioral context an agent could not infer from the schema.

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?

Purpose is front-loaded in the first clause and nearly every clause carries operational information. However, the storage/billing portion is a single long run-on sentence with deeply nested parentheses, which slows parsing; bulleting would preserve the content with less cognitive load.

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?

There is no output schema, so the description carries the full burden of explaining the return payload, and it does: identity, auth scopes, credit balance breakdown, plan activity, storage limits, billing location, period end, and scheduled changes. An agent has everything needed to interpret the result and act on it.

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?

Zero parameters, so there is nothing to disambiguate and the baseline is 4; the description instead spends its budget describing the returned fields (balance components, used_bytes vs limit_bytes, scheduled_change). No parameter meaning is needed or missing.

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?

Opens with a specific statement of what is returned: signed-in identity, the organization/workspace, and its credit balance. That distinguishes it cleanly from the sibling list_organizations, which enumerates many orgs rather than reporting the current credentials' account.

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?

Explicitly gives the trigger condition: 'Check it before creating anything', and explains the 402 plan_required and 402 storage_full outcomes the agent may hit when it skips this. It does not name a when-not or contrast with siblings such as get_options or list_organizations, so it stops 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.