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

Annotations already declare readOnly, idempotent, non-destructive, openWorld, so the safety profile is covered. The description adds genuinely non-redundant context: result ordering, that line items are omitted from results, and the required scope 'invoices:read' — useful for auth planning and for understanding output shape.

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 compact sentences: behavior/sort first, then filters, then constraints and scope. No filler, and the most important operational facts are front-loaded.

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 no output schema, it conveys what comes back (status and decimal amount summaries, no line items) and the auth requirement. The only material gap is silence on the q, page, and limit parameters, which an agent must infer from the schema alone.

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 carries the burden. It explains customer_id (UUID), status_id, and the issue_date_from/to pair, but never mentions the free-text q, page, or limit parameters, leaving three undocumented in both places.

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 ('Read one visible invoice page') plus scope details: sort order (newest invoice number first), the summary fields returned, and that line items are omitted. Siblings are all different resources (customers, items, locations, sales orders), so the resource noun alone differentiates it clearly.

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 clear usage context ('Read one visible invoice page', filter by customer UUID / status ID / issue date) and explicitly excludes adjacent operations ('no sending or payment operations'). It doesn't name an alternative tool for invoices, but no sibling overlaps on this resource.

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