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

readOnlyHint already covers the safety profile, and the description adds real behavioral context: totals are vendor-computed and unfiltered by date, plus the underlying endpoint. It does not describe what the totals contain, but for a read-only aggregate that is a modest gap rather than a blocker.

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?

Two compact clauses: the purpose leads, the disambiguation follows, and the endpoint trails as reference. No sentence is 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?

For a single-parameter read tool with full schema coverage and a readOnly annotation, the description covers what is needed to select and call it. Only the shape of the returned totals is left implicit, which is acceptable without an output schema but would be nice to have.

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 coverage is 100% and user_id already documents its source (list_users). The description only reinforces the semantic that the user is a staff user, adding little beyond the schema.

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 (sale totals for one staff user) and immediately disambiguates from the sibling sales_summary by noting there is no date filter. An agent can distinguish this tool from nearby siblings without opening a 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?

Explicitly names the alternative ('use sales_summary for a period') and the condition that selects it. Both the when-to-use and when-not-to-use are stated.

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