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

Annotations already declare readOnlyHint and destructiveHint, so the safety profile is covered. The description adds valuable behavioral context beyond that: it explains the account-scoped nature of the call and the private browser link that preserves agent identity through checkout, which is a meaningful side effect an agent needs to know about.

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?

Two sentences with no filler: the usage precondition is front-loaded, and the returned data is enumerated without redundancy. Every clause earns its place.

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 an output schema present, return-field details are already structured. The description covers when to invoke it, what to expect, and the identity-preserving checkout-link behavior. Nothing an agent needs to call it correctly 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, so there is no parameter syntax to document. The description clarifies that it operates on the connected account's identity, which is useful context and merits the baseline 4 for a parameterless tool.

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 states a specific purpose: a preflight check of the connected account's training balance and credits, returning welcome-credit status, available/reserved balance, balance packs, and a checkout link. It clearly distinguishes this account-level balance tool from siblings like get_training_job, which operate on individual jobs.

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 explicitly tells the agent when to call this tool — before quoting or creating a training job — which is clear, actionable guidance. However, it does not name alternatives or state when not to use it (e.g., when checking an existing job's status).

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