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

The annotations already declare non-read-only, destructive, idempotent, and closed-world behavior, while the description adds the required write scope. However, for a destructive mutation with 15 parameters, it does not clarify whether this is a partial update or a full replacement, nor what happens to omitted fields.

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 short sentences, zero waste, and the core action is front-loaded. The scope requirement is efficiently appended without burying the main point.

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 rich schema and annotations cover parameter definitions and safety characteristics, so the description does not need to repeat them. Still, for a destructive 15-parameter update, it is thin on partial-update semantics and expected mutation behavior.

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 100%, so all 15 parameters and their UUID/enum/date semantics are already documented by the schema. The description adds no parameter-specific meaning beyond identifying the record by ID, which justifies the baseline score.

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 and resource: update an existing invoice by ID. It is clearly distinguishable from create_invoice, delete_invoice, and get_invoice, though it does not name or contrast those siblings explicitly.

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?

It provides a prerequisite ('Requires invoices:write scope') but does not explain when to use this versus alternatives such as bulk_update or the create/delete invoice tools. Usage is implied by the tool name and scope requirement rather than explicitly guided.

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