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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds the Gripp API endpoint (invoiceline.get) and the returned fields, but says nothing about pagination behavior or row limits beyond what the schema states. Adequate but not enriched.

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 short sentences, front-loaded with purpose and scope; every sentence carries information. The trailing API endpoint reference is minor metadata but cheap and aids traceability.

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 simple read-only list tool with no output schema, the description names the fields returned, which compensates for the missing output schema. Pagination is covered by the schema, so nothing an agent needs to call it correctly is absent.

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 (including defaults for max_results and first_result) are already fully documented in the schema. The description adds only the provenance hint for invoice_id, which is already in the schema text. Baseline 3 applies.

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+resource ('List invoice lines') and enumerates the fields returned (description, amount, price, VAT), scoped to a single invoice id. It doesn't contrast itself with the sibling gripp_list_invoices, but the parameter hint ('from gripp_list_invoices') makes the parent/child relationship inferable.

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?

'Use this to see what an invoice contains' gives a clear triggering condition, and the invoice_id hint routes the agent to gripp_list_invoices first. No explicit when-not guidance or excluded cases, which keeps it short of a 5.

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