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 genuine workflow behavior: this is a two-step flow whose results must be handed to download_attachment, and it explains why the sibling tools cannot reach these rows. It does not mention pagination or rate limits, so it stops short of a 5.

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 tight paragraphs: purpose and output front-loaded, then the usage condition and next step. Every sentence earns its place with no filler.

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 an output schema present, return values need not be explained, and annotations carry the safety profile. The description covers purpose, routing, and the follow-up workflow; the only gap is the undocumented check_id and limit parameters.

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%, so the description must compensate. It names the conceptual search axes ('date range, payee, or amount'), covering start_date/end_date, payee, and amount, but omits check_id and limit entirely and gives no format details for dates or amounts. Partial compensation only.

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 invoice scans attached to CHECKS, with their FileIDs') and immediately scopes it against siblings by naming the exact situation (checks with no AP bill record). An agent can distinguish this from get_bills and download_invoices without opening any schema.

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?

Explicit when-to-use ('when a vendor was paid by check with no AP bill record'), names the alternatives that fail (get_bills, download_invoices) and why ('those rows show with no BillID'), and prescribes the follow-up step (pass FileID to download_attachment). Nothing is left to inference.

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