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

Adds substantial behavior beyond the read-only annotations: it returns an exact preview and a five-minute confirmation token, does not apply the change, and leaves saved financial data unchanged. It also states that the target client must be active and in the same workspace, which is important operational context.

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?

Three sentences, each front-loaded and purposeful. The first states the action, the second covers confirmation and non-mutation, and the third clarifies the return and that no change is applied—zero waste.

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?

Given no output schema and a simple one-object input, the description covers the essential lifecycle: preview, confirmation token, short expiry, and no application of change. It could say more about what the preview contains, but the core is complete for selecting and invoking the tool.

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?

Schema description coverage is 0%, so the description must carry parameter meaning. It adds useful constraints for the client target (must be active and in the same workspace) but does not explain the invoice_id or client_id fields, their UUID format, or how the nested input object maps to the operation.

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 verb and resource: preparing to move an invoice's client assignment. The final sentence explicitly distinguishes it from the applying sibling by saying it does not apply the change, so an agent can tell it apart from assign_invoice_client without opening either schema.

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?

Makes clear this is a preparatory preview that requires confirmation and returns a confirmation token, which implies it should be used before applying the change. It does not explicitly name assign_invoice_client as the follow-up alternative, but the surrounding context is clear enough to route usage.

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