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

Annotations already declare readOnlyHint, idempotentHint, non-destructive, closed-world. The description adds real substance beyond them by disclosing the forecast method (spend so far plus each remaining day at its weekday's recent average) and the 80% range, which tells an agent how much to trust the number. It does not mention any caveats about sparse data, but that is a minor omission against an already-strong annotation set.

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 with the resource and scope front-loaded and zero filler; the parenthetical methodology earns its place by explaining the calculation.

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?

An output schema exists, so return values need not be spelled out, and the description covers the method and all three param semantics. The remaining gap is that it never says how month-end vs quarter-end is chosen (there is no parameter for it), leaving the agent to guess that both horizons come back.

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%, so the description must carry the load — and it does: 'for the organization or one customer, feature or project' explains that all three optional params are scope selectors and that omitting them yields org-level results. The phrase 'one customer, feature or project' also hints they are single-value selectors. It does not state whether they can be combined, which keeps it from a 5.

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 names a specific verb+resource (forecast spend) and adds the scope (month-end and quarter-end, organization or one customer/feature/project), which clearly separates it from get_spend and month_end. It never explicitly names a sibling tool, so it stops short of a 5.

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?

Usage is implied: this is the forward-looking counterpart to get_spend's actuals. But there is no explicit 'use this when…' clause, no exclusions, and no pointer to month_end or get_spend as alternatives, so an agent must infer the routing.

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