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

The readOnlyHint and destructiveHint annotations already indicate a safe read operation. The description adds value by explaining plan.gating consequences for POST tools and the insufficient_tokens failure mode, so the agent knows why this read matters beyond its own result.

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 description is compact and front-loaded, opening with 'Free. Account overview' before moving to concrete usage rules. Every sentence adds operational value, including price computation and user-facing error handling, with no 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 zero-parameter read-only account tool with an output schema, the description covers everything an agent needs: what the tool returns, when to call it, how to compute cost, and how to react to the two likely failure conditions. Nothing essential is missing.

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 has zero parameters and schema coverage is 100%, so there is no parameter ambiguity to resolve. The description references meaningful output fields like plan.active and tokens_per_second, which indirectly clarifies the data an agent should read from the result.

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 clearly identifies the tool as an account/pricing overview: token balance, active plan, rate limits, and per-quality token prices. It also distinguishes itself from the video-generation sibling tools by being the read-only account-status tool to call first.

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 guidance: call this first to check balance, and before starting a video to compute price as tokens_per_second[quality] * duration_sec. It also provides concrete fallback behavior for no_active_plan and insufficient_tokens, which fully instructs the agent on when and how to respond.

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