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

With annotations already declaring destructiveHint=true and readOnlyHint=false, the description adds meaningful specifics beyond them: exact credit cost, the exact multiplier granted, and the 7-day duration. It aligns with the destructive/non-idempotent hints by framing the action as a spend, though it stops short of saying whether repeat purchases stack or what happens on insufficient balance.

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 sentence with zero filler, front-loading the cost and then the benefit and duration. Every clause earns its place.

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 one-parameter purchase tool with no output schema, the description covers the economics (cost, effect, duration) an agent needs to decide. Minor gaps remain around failure modes (insufficient credits) and whether purchases stack, but annotations already signal the irreversible spend.

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?

Only one parameter (api_key), and the schema already documents it at 100% coverage including the alternative auth methods. The description adds nothing about parameters, which is acceptable given the schema fully carries that burden; 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?

Specific verb+resource (buy a rate boost) with concrete parameters of the transaction: cost (200 ANANSI credits), effect (2x Commons and house-write limits), and duration (7 days). This clearly distinguishes it from siblings like buy_house_plan, buy_item, and boost_job, which purchase different things.

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?

No guidance on when to use this versus alternatives (buy_house_plan, buy_item, boost_job) or when not to. There is no mention of prerequisites such as needing sufficient credit balance, or whether the purchase can be repeated/stacked. Usage is only inferable from the name and effect.

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