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

Annotations already establish readOnly/idempotent/non-destructive behavior, so the description only needs to add context. It adds the flat 148-credit cost, the POST endpoint, and plan gating (Starter generally, Pro+ for formula_override), which are useful operational constraints.

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 dense but front-loaded: purpose, metric enumeration, cost, usage trigger, route, and auth in a compact block. The long metric list is warranted because there is no output schema and it clarifies exactly what this tool returns.

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 read-only metrics fetch with a fully described schema and safety annotations, the description covers cost, route, plan requirements, and when to use it. The only modest gap is that it never states the response shape, but the metric enumeration and schema largely compensate.

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 the baseline applies and the description does not need to explain parameters. It adds the formula_override privilege requirement and mentions metric names, but does not materially clarify the schema's already-detailed parameter semantics.

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 identifies the resource as profitability margins and return ratios, enumerates all 16 metrics, and explicitly scopes it to profitability questions. This separates it from the sibling efficiency/valuation/growth metric tools even though it never names a counter-tool.

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?

"Use when the user asks about profitability without naming a specific metric" gives an explicit positive trigger and an implicit exclusion. It also states the API route and plan requirements, but it does not name an alternative tool to use when a specific metric is named.

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