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

Annotations already declare readOnlyHint/idempotentHint/destructiveHint, and the description adds real operational context beyond them: the exact field set carried by these records, the fields they lack, and the important caveat that amounts are bare numbers with no currency, requiring get_organization_settings for currency_code. This is behaviorally useful guidance an agent would otherwise get wrong.

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?

Front-loads the purpose, then layers field composition, sibling routing, filters, and the currency caveat. Every sentence carries a distinct, decision-relevant fact 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 no output schema, the description compensates by enumerating the record fields, effectively documenting the return shape, and covers the currency pitfall. Pagination defaults live in the schema, so nothing needed to call it correctly 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 all six parameters are already documented in the schema. The description's filter mention ('by project, work order, or cost category') maps directly onto project_id/work_order_id/category_id without adding format or syntax detail, so the baseline 3 is appropriate.

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 project-scoped expenses') and pinpoints the UI location (Project → Costs → Expenses tab). It goes further by enumerating the record's fields and explicitly distinguishing itself from the sibling list_asset_costs, so an agent can route without opening either 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?

Names the alternative tool (list_asset_costs) and the exact condition that selects it — records on the main AssetLab Expenses page that carry invoice_number/po_number/category/asset links. The when-to-use-this-vs-that split is fully explicit.

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