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

Annotations already declare readOnly, idempotent, non-destructive and open-world, so the safety profile is covered. The description adds real behavior beyond that: it costs a keyed tier-quota slot, it deliberately avoids injecting facts, and it degrades gracefully ('falls back locally') when the engine ceiling is closed. The jargon ('keyed tier-quota slot') is undefined, which keeps it short of a 5.

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 dense sentences, front-loaded with the core action and followed by the return/fallback clause; nothing is wasted. The trade-off is heavy internal jargon ('refinement chips', 'engine ceiling') that trades brevity for opacity.

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 one-parameter tool whose annotations already carry the safety profile, the essentials are present, and the description partially compensates for the absent output schema by naming what it returns. It is nearly complete; the main gap is that the quota/fallback mechanics are referenced but not explained.

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?

With a single parameter at 0% schema description coverage, the description carries the burden. It conveys that the input is a rough student question, which gives the 'text' field implicit meaning, but adds no format, length, or content guidance beyond the schema's 1-2000 char bounds.

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?

The description gives a specific verb+resource ('sharpen rough student questions') plus a meaningful constraint ('without adding facts'), and even previews outputs ('detected niches and refinement chips'). It is clear on its own, but it never distinguishes itself from any of the ten ecca_* 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?

There is implied usage context ('rough student questions', and the fact that it consumes 'one keyed tier-quota slot'), which hints at when the cost is warranted. However, no when-to-use vs when-not guidance and no alternative sibling is named, so the agent must infer routing.

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