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

Annotations already establish the safe read-only, closed-world, non-destructive profile. The description adds meaningful behavior beyond that: it defines every returned amount field (awaitingAmount, futurePaymentsAmount, overdueAmount), notes the base currency, and declares the required invoice:read scope.

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?

Dense and front-loaded: purpose, return shape, scope default, alternative tools, and auth scope in a few tight sentences. Every sentence earns its place with no redundancy.

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?

Given no output schema, the description supplies the return fields and their meanings; annotations cover safety; schema covers parameters. An agent has everything needed to choose and call this tool correctly.

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 three parameters are already documented. The description largely restates movement behavior that the schema already explains and adds no syntax beyond it. Baseline 3 applies when the schema does the heavy lifting.

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 and resource ('Get unpaid invoice totals for a company') and immediately distinguishes itself from siblings by naming the alternatives for related-but-different goals. An agent can tell this is a summary tool, not a list or an aging report.

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?

Explicitly routes the agent to get-overdue-invoices or get-aged-receivables-v2 for amounts by customer/age and to list-invoices for individual invoices. It also states the scope constraint ('Covers sales invoices unless movement is out') and the required permission, leaving little inference.

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