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

readOnlyHint=true already tells the agent this is a safe, non-mutating read, so the annotation carries the safety burden. The description adds real value by disclosing the return contents (balance plus per-resolution pricing), which matters most here because there is no output schema. It stops short of noting currency, units, or whether pricing can change.

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?

A single sentence that front-loads the most important return value (credit balance) and then the secondary one. No filler, no repetition of the title.

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 with no output schema, the description adequately covers what comes back, which is the only thing an agent needs to decide to call it. Minor gaps remain around currency/units and whether the pricing list is exhaustive for all resolutions.

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 nothing for the description to disambiguate and the baseline of 4 applies. The schema's empty properties object matches the description's non-mention of inputs.

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?

Rather than restating the name, the description states the concrete payload: credit balance and per-resolution price per second of video. That tells an agent exactly what 'account' means here, and no sibling (create_upload, get_task, list_tasks, upscale_video) covers the same resource. It lacks an explicit verb but the resource is unambiguous.

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?

Usage is only implied: an agent can infer this is the tool to call to check credits before or after an upload. There is no explicit 'use this when...' statement, no mention of alternatives, and no note that it takes no arguments, which would have made it clearly self-selecting.

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