create_invoice

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

Annotations only declare that this is a non-destructive write with no open-world access; the description adds the important non-obvious fact that the result is a draft, not a sent invoice, which the annotations do not convey. It still says nothing about whether client_id must pre-exist or what errors occur on an unknown client, and the return value is covered by the output schema.

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 sentences, zero waste, with the draft-status constraint front-loaded ahead of the lifecycle pointer. Nothing could be removed without losing 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?

The output schema and annotations carry the return value and safety profile, so the description does not need to. However, for a 6-parameter creation tool with only 50% schema coverage, it is thin: no mention of what client_id must reference, that items accept quantity/unit_price formats, or defaults for tax_rate, dates, and payment terms.

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 only 50% and the description adds no parameter meaning at all. Six parameters including required client_id, items, and notes are left entirely to the schema, and the description never compensates for the undocumented halves despite the low coverage.

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+resource ('Create a draft invoice') and immediately distinguishes it from the downstream sibling mark_invoice_sent. It does not differentiate from create_quote or convert_quote_to_invoice, which also produce invoice-like documents, so an agent must still infer when to build from a quote versus from scratch.

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?

Gives one clear sequencing rule: use mark_invoice_sent once the invoice has gone to the client, which implies this tool creates the pre-send state. It provides no exclusions or alternatives for the other invoice-producing siblings (convert_quote_to_invoice), so guidance is implied rather than complete.

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