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

Annotations already declare a pure read-only, idempotent, non-destructive, non-open-world calculation, so the safety profile is covered. The description adds the deterministic input→output mapping via the worked example, but says nothing about edge cases (e.g. zero contribution → infinite time) or limits beyond what the schema constrains.

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 sentences, front-loaded with the computed outputs and followed by a single compact worked example. No filler; every clause earns its place.

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 and annotations carry the safety profile, so the description needn't explain return values or side effects. Parameters are fully documented, and the example confirms the calculation semantics — nothing essential is missing.

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%, so the schema already documents every parameter, making 3 the baseline. The worked example goes beyond the schema by showing how expenses, savings, contribution, and target combine into concrete outputs, adding interpretive value.

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 (Calculate) and resource (emergency fund coverage: months covered, target, gap, months to close). The listed outputs make it unmistakably distinct from siblings like fire_number or compound_interest without opening their schemas.

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 example implies the scenario (given expenses/savings/contribution/target, compute coverage and path to target), so usage is inferable. However, it never states when to prefer this over fire_number, compound_interest, or cost_of_waiting, nor any prerequisites, so guidance is only implied.

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