list_costs

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

Annotations already provide readOnlyHint=true, and the description does not contradict this. Beyond the annotation, the description discloses the return shape '{costs[], pagination}', which gives the agent insight into the result structure and pagination behavior. This is useful contextual information not present in the annotation.

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?

The description is a single sentence plus a return type snippet. It is front-loaded with the verb 'List', and every word adds value: the resource, the purpose, the filter dimensions, and the return shape. No fluff or redundancy.

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 5-parameter list tool with no output schema, the description provides the return shape ('{costs[], pagination}') and the purpose, which covers the essential context. It does not explain every parameter, but the schema handles that. It could mention default sorting or explicitly state read-only, but the annotation covers the latter, so it is sufficiently complete.

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% (all 5 parameters have descriptions), so the baseline is 3. The description mentions filtering by 'date and cost group', but this simply mirrors the schema parameter descriptions without adding new meaning. It does not compensate with additional parameter-level context.

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?

The description opens with a specific verb and resource: 'List expense records'. It also adds the purpose 'for margin/profit analytics' which distinguishes it from other list tools like list_orders or list_customers. This clearly identifies what the tool does.

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?

The phrase 'for margin/profit analytics' gives a clear context for when this tool is appropriate, and the mention of 'by date and cost group' hints at filtering use cases. It does not explicitly exclude alternatives, but the sibling tools (e.g., create_cost, list_orders) are clearly different resources, making the usage intuitive.

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