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

With destructiveHint=true already declared, the description adds meaningful behavioral context beyond the annotation: it moves the invoice out of draft and adds the amount to the client's balance. It does not state whether the transition is reversible, which would complete the picture for a mutation.

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 tight sentences with the key distinction (no email) and the state effect front-loaded, followed by the backing endpoint. 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 one-parameter mutation with no output schema, the description covers the essential side effects and the underlying endpoint. It is nearly complete, missing only reversibility/return behavior, which is minor here.

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 100% and the single invoice_id parameter is fully documented (hashed id with example). The description adds no format or constraint detail beyond the schema, so the baseline of 3 applies.

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 ('Mark a draft invoice as sent') with the crucial scope qualifier 'WITHOUT emailing it', which cleanly separates it from the sibling invoiceninja_email_invoice. An agent can tell exactly what this does and how it differs from the email path without opening a 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?

The phrase 'WITHOUT emailing it' implicitly routes the agent here instead of email_invoice when no email should be sent, giving clear usage context. It stops short of explicitly naming the alternative or stating when the tool should not be used.

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