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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so safety needs no repetition. The description adds real behavioral context beyond that: pricing comes from 'currently verified standard rates', long-context tiers are applied, and models without a verified price are returned as unavailable with a reason. It still doesn't say what the output looks like or which currency is used.

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 dense sentences with zero filler, front-loading the action and scope, followed by the pricing and edge-case behavior. Nothing is redundant with the annotations or schema.

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 full schema coverage, annotations, and an unambiguous calculation model, the only real gap is that no output schema exists and the description doesn't state the shape of the returned estimate or its currency. That gap is minor but not trivial for a comparison tool whose value is in the numbers it returns.

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 documents every parameter and the baseline is 3. The description nonetheless clarifies the interaction between parameters with the formula 'tokens per request times requests', which explains how requests combines with input/output token counts, and notes the long-context tier behavior tied to those token counts.

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 gives a specific verb and resource ('estimate the cost of a workload') and scopes it to 'up to six models' using verified standard rates, so an agent can tell this is a calculator rather than a raw price lookup like get_model_prices. It never names a sibling tool, so the differentiation is inferred rather than stated.

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 only implied: an agent can infer this is for budgeting or pre-run cost comparison, but the description never states when to use it over get_model_prices or compare_subscription_plans, nor any exclusions. No explicit when/when-not guidance is given.

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