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

Annotations already cover read-only safety, but the description adds real behavioral context beyond them: results are the single best offer per model, non-standard price types and free promos are filtered out by default, and rows carry specific fields. It does not discuss pagination or result ordering ties, but the filtering defaults are the material behavior here.

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?

It is front-loaded with the resource and ranking basis, then the input modes, then the filtering rules, then the row shape — a sensible order with no filler. The middle sentence is densely packed with several qualifiers, which is efficient but slightly harder to parse than a split would be.

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?

For a 12-parameter tool with no output schema, the description compensates by enumerating return fields (monthly_cost_usd, prices, context, checked_at, card_url, cite line) and explaining default filtering. The main residual gap is that it never says how ranking ties or empty results behave, but nothing essential for calling it correctly 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 baseline is 3; the description adds value by explaining that a preset "fills tokens, min_context, category" while "your own values win" — a precedence rule the schema does not encode. It also clarifies the default exclusion behavior behind include_free and include_special, though most other parameters are left to 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?

The description opens with a specific resource and scope: "The cheapest offers for a whole monthly workload, ranked by monthly cost in USD." The "whole monthly workload" framing distinguishes it from per-call/per-token pricing siblings such as cheapest_models or get_model_prices, so an agent can pick it without opening the schema.

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?

It states the two input modes ("give a preset ... and/or your own tokens a month") and routes the agent to workload_presets for preset definitions. It also explains that free promos and batch/flex/priority/regional prices are excluded "unless asked," tying the flags to a use case. It stops short of explicitly naming when to prefer cheapest_models or estimate_cost instead.

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