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

No annotations are provided, so the description carries the full burden. It does disclose real behavior beyond the schema: the tool is ungated for Free users and returns a friendly response when the key isn't recognized. However, it says nothing about auth requirements, rate limits, or what happens with an unknown key beyond 'friendly', leaving meaningful behavioral gaps for a no-annotation tool.

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?

Purpose and scope are front-loaded in the first sentence, followed by gating behavior and trigger phrases. It is efficient, though the parenthetical about capabilities() and unrecognized keys is somewhat wordy for the value it adds.

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 zero-parameter, read-only lookup with an output schema, the description covers everything an agent needs: what it returns, who can call it, and when to trigger it. Return-value documentation is correctly left to the output schema.

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 for the description to disambiguate; the baseline for a parameterless tool is 4. The listed fields (plan, seats, users) describe the response shape rather than inputs, and the output schema already covers returns.

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 ('Show account info') and enumerates the returned fields (plan, seats, users), so the agent knows exactly what the tool surfaces. It references capabilities() but only to explain gating parity, not to discriminate when this tool should be chosen over siblings like upgrade_link or capabilities.

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 'Triggers on:' list gives concrete invocation phrases ('what's my plan', 'my account', 'my subscription', 'account info') plus an explicit eligibility condition ('works for all users including Free'). That is strong positive guidance, but there is no when-not guidance or named alternative for adjacent questions such as upgrading a plan.

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