tokmeter_forecast

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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered; the description adds useful behavioral detail by describing what is computed (daily/weekly/monthly averages, three projection horizons, trend classification). It stops short of stating anything about forecast reliability or data-volume preconditions.

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?

Three front-loaded sentences: capability, then outputs, then trend dimension — no filler. The trailing "Use this for budgeting" is the least valuable line and is the one most likely to cause sibling confusion.

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 no output schema, the description appropriately characterizes the return payload (averages, 7/30/90-day projections, trend label), and all three parameters are fully documented in the schema. Missing is any note on how much historical data is needed for projections to be meaningful, which matters for a forecasting tool.

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?

With 100% schema description coverage including an enum for scope and examples for providers, the schema does the work and baseline 3 applies. The description never references the scope/project/providers filters, so it adds nothing beyond the schema — notably it doesn't clarify whether the 'next 7/30/90 days' output varies with the chosen scope.

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 — projects future AI token costs from historical burn rates — and enumerates the exact horizons (7/30/90 days) plus trend direction. It does not explicitly differentiate itself from close siblings like tokmeter_budget or tokmeter_budget_alert, so the agent must infer the boundary.

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 this for budgeting" gives implied context, but it is the weakest and most ambiguous sentence: it overlaps conceptually with tokmeter_budget and tokmeter_budget_alert without naming either as an alternative. No when-not-to-use conditions or prerequisites (e.g., minimum history required) are given.

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