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

Annotations already declare readOnlyHint=true, openWorldHint=false, destructiveHint=false, so safety is fully covered. The description adds nothing behavioral beyond that: no indication of whether the estimate is an approximation, what assumptions it makes about cadence, or how optional fields like modelIds/autoRunWeekdays affect the result.

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 front-loaded sentence with no waste; the key inputs are enumerated immediately. It is arguably too terse for the parameter surface, but it is structurally efficient.

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 7 parameters (5 required), no output schema, and low schema coverage, the description should explain what the estimate returns (units, breakdown, whether it is per-model). None of that is present, so an agent cannot predict the response shape or the effect of several required parameters.

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 only 29% across 7 parameters, so the description must compensate. It does partially, by mapping 'prompt count', 'models', and 'cadence' to promptCount, modelIds, and autoRunFrequency, but it says nothing about advertiserProjectId, autoRunWeekdays, or how the frequency enum interacts with weekday selection.

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 (Estimate) and resource (Navi credit usage) and names the three drivers of the calculation (prompt count, models, cadence). It is clearly distinguishable from read/create siblings like get-llm-monitoring or create-llm-run, though it never explicitly contrasts itself with them.

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 description gives no when-to-use context: no prerequisites, no note that this is a pre-purchase/pre-setup estimate rather than a post-hoc usage report, and no pointer to alternatives such as get-monitoring-stats for actual usage. Usage is only implied by the resource being 'setup cost'.

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