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

Annotations already declare it is a non-read-only, non-destructive, non-idempotent write; the description adds that it creates a *draft* (not sent) and discloses per-call cost of $0.01 with no charge on failure — useful for retry/rate decisions. It doesn't warn that calling twice on the same quote likely produces duplicate drafts, which matters given idempotentHint=false.

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, all front-loaded with the core action first, then the edge-case parameter, then the cost model. Nothing is redundant and each sentence 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?

There's no output schema, and 'draft invoice ... ready for invoices_send' conveys essentially what comes back and its state. Missing is an explicit statement of the return identifier and the duplicate-conversion caveat, the only things an agent would still need to guess.

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 100%, so the baseline is 3; the description adds real meaning by explaining *why* mark_accepted exists — the customer accepted out-of-band via email or phone — a scenario the schema text does not convey. quote_id is passed through implicitly, which is fine since the schema documents it fully.

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 precise verb and resource ('turn an accepted quote into a draft invoice') plus the mechanics (same customer and lines), which distinguishes it cleanly from invoices_create and invoices_send. It also names the follow-up sibling, so an agent knows exactly where this sits in the workflow.

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 the precondition (the quote must be accepted) and an explicit alternate path: if acceptance happened by email or phone, pass mark_accepted: true. It also points to invoices_send as the next step. It stops short of saying when to use invoices_create instead of converting a quote, but the context is clear.

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