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

Annotations already declare idempotentHint=true and non-destructive/non-readonly, so the safety profile is covered. The description still adds real value beyond them: it discloses that a monetary charge is incurred, that the amount equals credits.owed, and that the charge is only made once – a financial side effect an agent must know before calling.

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 short sentences with zero filler; the precondition is front-loaded and the idempotency note trails as a caveat. Every clause carries information.

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 one-parameter tool with rich annotations, the description covers precondition, cost, and repeat-call behavior – sufficient to call it correctly. Slightly short of 5 because it doesn't say what happens when the project is not in needs_credits status (error vs. no-op).

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?

There is only one parameter and the schema already documents it at full coverage ('The id returned by split_into_layers'), so the description adds nothing parameter-specific. Baseline 3 applies when the schema does the heavy lifting.

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?

States a specific action (pay the extra credits owed) tied to a specific precondition (split with status needs_credits) and a concrete outcome (layer files become available). This clearly separates it from get_credits, get_layers, and split_into_layers, which neither pay nor gate file access.

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?

The precondition 'For a split with status needs_credits' tells the agent exactly when this tool applies, which is the key routing signal against the sibling tools. It does not state what to do if the status is something else, but the positive condition is unambiguous.

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