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

Without annotations, the description carries the full burden. It discloses the return format (sorted by absolute percentage change with direction labels), which is useful. However, it omits other behavioral details such as permissions, rate limits, or whether the data is live or cached, leaving some gaps.

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?

The description is three sentences: purpose, return format, and usage examples. It is front-loaded with the core function and every sentence earns its place by adding distinct value for an agent.

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 simple query tool with rich schema documentation and no output schema, the description covers purpose, return format, and usage. It lacks only minor details like default values (already in schema) or read-only nature, but it is largely 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 description coverage is 100%, so the schema already fully documents both parameters. The description only indirectly references the 'given period' (mapping to the 'days' parameter) and adds no new parameter semantics, making the baseline 3 appropriate.

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 states a specific verb ('Find') and resource ('models whose prices changed the most') and clarifies the output ordering. However, it does not explicitly differentiate from sibling tools like check_price_drift or get_pricing_history, leaving the agent to infer that this tool focuses on ranking by absolute change over a period.

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 provides clear usage context with example questions ('which models got cheaper this month?'), which effectively signals when to use the tool. It does not offer explicit when-not-to-use guidance or name alternatives, so it falls short of a 5.

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