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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds genuinely useful behavioral context beyond that: 1-day trial, no card, no KYC, on-chain USDC payment on Solana, and that a human principal owns billing — all of which shape how the agent should describe terms to a user.

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?

It is front-loaded with the purpose, but the body is a dense block of hard-coded price points and plan names that reads more like marketing copy than tool guidance. Some of that detail is defensible given there is no output schema, but the sentence 'A human principal owns billing and Approval Inbox' is loosely connected to the tool's function.

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 parameters and no output schema, the description usefully conveys the substance of what the tool returns (plan tiers, prices, trial terms). It is largely complete for a simple read tool, though it omits any note on return format or currency handling beyond the USDC mention.

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?

The tool takes zero parameters, so there is nothing to document and the baseline is 4. The description does not need to compensate for any schema gap.

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?

States a specific verb and resource: 'List Agent Control plans and trial truth,' which tells the agent this is a read tool returning plan/trial information. However, it never distinguishes itself from near-neighbor siblings like meter_pricing or start_trial, so the agent must infer the boundary.

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 or when-not-to-use guidance. The description lists prices but never says to call this before start_trial, before create_checkout, or instead of meter_pricing, even though several siblings occupy adjacent territory.

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