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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description adds a genuinely non-obvious behavioral fact: amounts are bare numbers with no currency, so a currency_code lookup is required before quoting a figure. It does not describe ordering or default sort, which is a minor gap.

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 tight sentences with zero filler; the core action is front-loaded and the currency caveat, the highest-value detail, is placed immediately after the filter list.

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?

For a read-only list tool with a fully documented schema, the description covers purpose, filters, and the one result-format trap an agent would otherwise fall into. Pagination behavior is left to the schema, which already states all pages are fetched automatically, so nothing essential is missing.

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 every parameter is already documented in the schema, and the description's status enumeration mirrors the schema rather than extending it. No added syntax, defaulting, or interaction semantics beyond what the schema provides.

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 ("List invoices") and immediately scopes it with the three supported filter axes (status, vendor, project). An agent can distinguish it from the get_invoice / create_invoice / update_invoice siblings from the description alone.

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 actionable guidance on which filters exist and, critically, routes the agent to get_organization_settings when a currency must be stated. It stops short of explicit when-not-use or escalation rules (e.g., when to prefer get_invoice for a single record), so it is clear context without exclusions.

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