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

The description discloses behavioral traits beyond annotations: ownership by the caller, server-side computation of totals from line_items and tax_rate, and the initial 'draft' status with a clear state transition. Annotations only indicate it is not read-only and not destructive, so the description adds meaningful behavioral 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?

The description is two sentences with no redundancy. Purpose and constraints are front-loaded, and the behavioral notes are packed efficiently. 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?

For a creation tool with no output schema, the description covers the essential facts: what is created, ownership, optional additions, computed totals, initial status, and the next step. Minor gaps (e.g., behavior with no line items, validation of client_name) are not critical 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 56%, and the description enhances meaning for deal_id, line_items, and tax_rate (linking, seeding, and total computation). However, it does not clarify notes, client_email, or provided payment_terms beyond what the schema already mentions (e.g., examples). It adds some value but does not fully compensate for the undocumented parameters.

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 verb ('create'), a distinct resource ('draft invoice'), and key constraints ('owned by the caller for a client', 'optionally seeded with line items and linked to an existing deal'). It clearly distinguishes this creation tool from sibling tools like update_invoice, send_invoice, or convert_deal_to_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 gives clear context: this tool creates a draft invoice stub. It explicitly routes the next step ('call send_invoice to mark it sent'), which provides workflow guidance. However, it does not name alternatives like update_invoice for existing invoices or convert_deal_to_invoice for converting a deal, so it lacks explicit exclusions.

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