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

Annotations already declare readOnlyHint=false and destructiveHint=false, so the safety profile is covered. The description usefully adds that the estimate is not sent and that a review link is returned, which is genuine behavioral context, but it says nothing about permissions, idempotencyKey handling, or what happens on repeat calls.

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 short, front-loaded sentences with no filler. Slightly informal phrasing ('Open the link to review it') but every sentence carries 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?

With 8 parameters at 0% schema coverage, no output schema, and nested item objects, the definition is under-specified. It omits any explanation of the line-item structure, date/currency semantics, or the idempotency key that a mutation tool of this complexity needs.

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 0% across 8 parameters, so the description must carry the burden and largely does not. Only the clientId requirement is implied ('customer who is already in this business'); items, notes, currency, issueDate, expiryDate, and idempotencyKey are left entirely unexplained.

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 (save) and resource (draft estimate) plus a scoping condition ('for a customer who is already in this business'). This implicitly separates it from the sibling create_draft_invoice, though it never names the sibling or explicitly contrasts the two.

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 'for a customer who is already in this business' hints at a prerequisite (the client must already exist, e.g. via find_clients) and 'It is not sent' hints at the draft vs. send distinction. However, no alternative tool is named and no explicit when-to-use/when-not guidance is given.

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