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

With no annotations, the description carries the full burden and does real work: it discloses the auth requirement (linked operator key), the specific error outcome for unlinked keys, and a non-obvious data caveat that bonus funds are excluded from cash balance. It doesn't state read-only semantics explicitly or mention rate limits, but a status call's behavior is otherwise well covered.

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, front-loading what is returned before the prerequisites. Every clause carries information — the field list, the bonus-funds caveat, the key requirement, and the error code — with no filler.

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?

No output schema and no annotations, so the description must cover both return content and operational requirements, and it does: it enumerates the returned fields and specifies auth plus the error case. An agent can decide to call it, prepare the key, and interpret results without further information.

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 the baseline is 4; there is nothing for the description to disambiguate. It correctly adds no parameter commentary, since none is needed.

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?

Names the specific resource (linked Lightning Faucet account status) and enumerates the exact contents: cash balance with bonus funds excluded, deposited/withdrawn totals, daily streak, and earn summary by source. This is enough to separate it from generic balance tools like check_balance, though it never explicitly contrasts itself with those siblings.

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?

Gives a concrete precondition ('needs an operator key linked with link_account') and the failure mode for unmet preconditions ('unlinked keys get account_not_linked'), which tells an agent when the call will succeed and which sibling to run first. It stops short of stating when to prefer this over check_balance or get_agent_analytics.

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