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

With no annotations, the description carries the full burden and delivers: abuse guards (one key per IP per day), 7-day expiry, no paid conversion, and a single-display key that must be saved immediately. These are consequential behaviors an agent could not infer from the schema.

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?

Usage condition comes first, then mechanism, then guards, then the critical save instruction. Every sentence is load-bearing; nothing is restated for padding.

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 explanation is unnecessary, and the description still covers side effects (rate limit, expiry, non-convertibility) and the one-time key handling. Nothing an agent needs to call this safely is missing.

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 no parameter semantics for the description to compensate for. It does not need to describe inputs, and it doesn't waste words doing so.

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 — mints a 25-call trial API key — with concrete scope (25 calls, no card, no account). It is instantly distinguishable from siblings check_balance and generate_captions.

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?

Explicitly names the trigger condition (no API key configured, user wants to try the free tier) and adds a hard exclusion: only call after the user agrees, never mint silently. This is exactly the when/when-not guidance an agent needs before invoking a provisioning tool.

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