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

readOnlyHint=true already covers the safety profile, and the description adds the return-shape behavior: results are grouped by status, and earnings are restricted to employees. That grouping behavior is not derivable from the schema, so it adds real value beyond 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?

A single dense sentence front-loads the resource and measures, closing with the underlying endpoint. There is mild redundancy with the schema's own enum descriptions, but nothing wasted.

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 six parameters and no output schema, the description does enough: it names the three kinds, the three measures, the default, the employees-only restriction, and the status/date filters. Only the shape of the returned breakdown remains implicit.

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 every parameter (id, kind, status, measure, date_from, date_to) is already documented in the schema. The description largely restates enum values and the count default without adding format or edge-case detail, so the baseline of 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: aggregated lesson totals per student/customer/employee, with explicit measures (count, duration, earnings). This distinguishes it from listing tools like teachworks_list_lessons, though it does not name the overlapping sibling teachworks_get_employee_earnings.

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 description implies usage (aggregate totals rather than individual lessons, optional status/date filtering) but never states when to prefer this tool over alternatives such as teachworks_get_employee_earnings or teachworks_list_lessons. Context is present, but no exclusions or routing guidance.

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