Deal check

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

Annotations already cover read-only/idempotent/open-world/non-destructive, and the description adds genuinely new behavior: the explicit cost of 2 requests, the internal sources it calls (chart + sellers), the scoring heuristic, and the `reasons` output field. That is well beyond what the annotations declare.

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?

Front-loaded with the purpose and result before any methodology, and each sentence earns its place (bands, cost, reasons field). The heuristic paragraph is dense but justified since it explains how to interpret the output; only the '(documented, not Torob's)' aside borders on expendable.

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 carries the return-value burden and does cover the score scale, the `reasons` field, and the request cost. It stops short of enumerating the full response shape, but for a read-only scoring tool this is nearly complete.

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 baseline is 3, but the description adds real meaning: it explains how the price input is used (percentile against the past year's weekly minimums, penalty when above today's cheapest usable offer) and confirms the default. This clarifies the parameter's role in the algorithm, not just its format.

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?

Opens with a specific question ('Is this a good price?') and states exactly what it produces: a 0-100 score derived from price history and today's offers. This clearly separates it from data-returning siblings like tb_price_chart or tb_price_history, which report numbers rather than render a verdict.

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 framing question plus the score bands (70+ good deal, 40-69 fair, below 40 wait or shop around) make the intended use case and interpretation clear. However, it never names a sibling as an alternative or states when-not to use it (e.g. vs tb_cheapest or tb_best_value), so an agent must infer the routing.

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