Show my daily allowance

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, but the description adds real behavioral context beyond them: it is free, never counted against the quota, reports both anonymous (5/day) and keyed (25/day) ceilings, and points to the key signup. Auth requirements and rate limits are disclosed, which is exactly what the annotations cannot convey.

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, output contents front-loaded before the quota/auth caveats, with no filler. The trailing signup URL and parenthetical are slightly dense but genuinely actionable, so the trade-off is acceptable.

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?

An output schema exists, so return-value detail is optional; the description going further and enumerating the fields is a bonus. Auth needs, quota tiers, reset timing, and cost are all covered, leaving no gap an agent would need to guess at for this parameterless read tool.

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 and there is nothing further for the description to disambiguate. The statement that it costs no lookup is a useful semantic note about invocation but is not a parameter concern.

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 ('Show your own allowance') followed by an enumerated list of what is returned: plan, daily limit, lookups used today, remaining, reset time, credit balance. It is unmistakably distinct from the lookup/enrich siblings, which all consume allowance rather than report it.

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 clear context for when to call it (checking your allowance) and states the free/unmetered condition plus the anonymous-vs-key limits that shape usage. It does not explicitly name an alternative tool or a 'do not use when' case, but the sibling set contains no near-equivalent, so routing risk is low.

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