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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and closed-world, so the safety profile is covered. The description adds nothing: no return shape, no aggregation semantics, no pagination or required context, and no explanation of what 'by-site' grouping means. It does not contradict the annotations.

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?

It is short, but the brevity comes from repetition (the same path stated twice) rather than from packing in useful information. The content is not front-loaded with anything an agent can act on.

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 0% parameter documentation, a nested/free-form query object, no output schema, and no annotations about return values, the description leaves an agent with essentially no basis for calling the tool correctly. It should at minimum explain the site grouping and how to pass the site filter.

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% and both parameters are opaque ('query' as free-form additionalProperties, 'params' empty object). The description supplies no meaning, format, or examples for either, and does not mention the site identifier that the endpoint name implies.

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 only repeats the endpoint path 'GET /api/expenses/by-site' twice plus an opaque operation ID; it does not state in words what the tool returns (expenses grouped/rolled up by site) or how it differs from siblings like get_expenses_by_lease or get_expenses_summary. This is effectively a restatement of the name/title.

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?

There is no guidance on when to use this tool, when not to, or which sibling (e.g. get_expenses_04045..., get_expenses_by_lease, get_expenses_summary) covers adjacent needs. The only instruction, 'describe_operation provides native request schemas,' points at another tool rather than describing this one's usage.

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