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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuine behavioral context beyond that: results span all regions and come back newest-first, which shapes how an agent consumes the output.

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 sentences, zero waste: the core behavior leads and the concrete example follows. Every clause carries information an agent would otherwise have to infer.

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 an output schema present and all four parameters optional with documented defaults, the description covers what an agent needs to decide and call. It stops short of noting the result cap or whether empty windows return an empty list, but those gaps are minor given the structured fields.

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 75%, so the schema already documents days and locale; the description only restates the day window and implies a product example. It says nothing about the limit parameter or the default of 20 results, so it adds little beyond structured data.

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?

Specific verb and resource: 'List monthly subscription price changes AISub recorded across all regions in the last N days, newest first.' Scope and ordering are explicit, and 'recent N days' implicitly separates it from get_price_history, though no sibling is named outright.

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 example question ('which countries changed ChatGPT prices this month?') gives a clear trigger context for invocation. It does not state exclusions or point to compare_prices / get_price_history when a longer window or cross-product comparison is needed.

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