billy_send_invoice

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

With no annotations, the description carries full burden. It discloses the confirm dry-run vs. execution behavior and the email payload structure. However, it omits prerequisites, success/error responses, and other backend effects.

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 well-structured sentences: purpose, WRITE nature with confirm, and email payload format. No redundant or extra 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 tool with 3 parameters, nested object, and no output schema, the description covers the core action, the confirm safeguard, and email format. Missing potential error cases or return values, but sufficient for correct invocation.

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 coverage is low (33%), but the description compensates by detailing the email object fields (to, cc, bcc, subject, message, attachPdf). It also clarifies the confirm parameter's role. Some fields like replyTo and country are omitted.

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 clearly states 'Send an invoice by email via Billy,' specifying the verb (send) and resource (invoice by email). It distinguishes from sibling tools like billy_approve_invoice or billy_create_invoice.

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 description explains the WRITE nature and the confirm:true requirement for actual execution, which guides when to use. However, it does not explicitly state when not to use or provide comparisons to alternatives.

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