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

Annotations already declare this a read-only, idempotent, closed-world operation, so the safety profile is covered. The description adds useful payload context, namely that results include MoM change, constituents, the headline, and that the data is CC BY 4.0 licensed. It does not address pagination, freshness, or how many constituents are returned.

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 compact sentences, front-loaded with the core resource and what it contains, with the optional mode and license trailing. Slight density in the tier list but nothing 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?

With no output schema, the description carries the return-value burden and does so by enumerating tier medians, subscription prices, MoM change, constituents, and headline. Only minor gaps remain, such as response shape and freshness cadence, which are not essential to invoking it correctly.

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 both edition and history are already documented with format, default, and example. The description only restates the optional history behaviour ('full edition history'), adding no format or validation detail beyond the schema; baseline 3 applies.

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 resource and verb: a monthly index of AI prices, broken into median verified API list prices per tier plus typical subscription prices. That tells an agent it is an aggregate index, distinct from per-model tools like get_model_prices, though it never names that sibling explicitly.

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?

Usage is only implied: the 'Optionally the full edition history' clause hints that history is opt-in, and 'monthly index' implies aggregate rather than per-model queries. There is no explicit when-to-use-this-vs-alternative guidance covering get_model_prices, estimate_api_cost, or compare_subscription_plans.

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