price_changes

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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds what the report actually contains (drops, increases, free models, model counts), which is useful content-level context, but it says nothing about aggregation window behavior, freshness, or data source. Adequate but not rich.

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?

A single front-loaded sentence that enumerates the report's contents with no filler. It is slightly list-like and could be tightened, but nothing in it is wasted.

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?

An output schema exists, so return-format explanation is rightly omitted, and the three parameters are simple. However, the description leaves the `limit` parameter unexplained and introduces a 'since a month' claim inconsistent with the documented 3-month default, gaps an agent would notice when setting the window.

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 67%: `since` and `response_format` are documented in the schema, while `limit` is not. The description's 'since a month' loosely gestures at the comparison window but actually conflicts with the schema's own default of '3 months ago', so it adds ambiguity rather than meaning for the one parameter it touches. Baseline 3 is 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 names a specific resource (LLM pricing) and an explicit scope (changes over a period), enumerating the outputs: biggest drops/increases, newly free models, models added/removed. It does not, however, distinguish itself from close siblings like model_price_history or compare_providers, leaving the agent to infer the difference.

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?

There is no when-to-use guidance, no stated alternatives, and no exclusions. Given siblings such as model_price_history (per-model history) and compare_providers (cross-provider comparison), the agent needs a routing rule that this description never supplies.

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