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

Annotations already declare readOnly=true, idempotent=true, openWorld=false, destructive=false, so the safety profile is covered. The description adds that the output is a monthly figure adjusted by retention, which is modest but useful context; it does not disclose pricing-model assumptions or whether cost is per-provider.

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 tight sentences with the use case front-loaded and the return value second. Nothing is wasted, though the second sentence slightly overlaps what the schema already implies.

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 correctly states the headline return value (monthly cost at a given volume with retention adjustment), which is enough to call the tool. Minor omission: it never notes that only one provider is evaluated per call.

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 enum provider list, default avg_log_bytes (4096), default retention_days (30), and requests_per_day are already fully documented. The description references request volume and retention but adds no format or unit detail beyond the schema.

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 concrete verb and resource: it budgets "LLM observability tooling" and returns a monthly cost. The 'observability' scope does distinguish it from eval-, agent-loop-, and rag-pipeline-cost siblings, though no sibling is named explicitly.

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 a user needs to budget LLM observability tooling" gives a clear triggering scenario, but with 11 cost-calculator siblings there is no when-not guidance and no routing to alternatives such as provider-cost-calculator or eval-cost-calculator.

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