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

Annotations already declare readOnly/idempotent/non-destructive; the description usefully adds no-auth, a 5-query session cap, and sample usage. However, it muddles the behavioral picture by first quoting a 0.01 USDC/query price and then saying 'FREE preview — no key, no payment', which is internally inconsistent.

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?

The description is padded with emojis, repeated free/no-key messaging, and promotional sample questions. The useful signal (free preview, listing, 5-query cap) is buried in redundant sales copy rather than front-loaded cleanly.

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?

It gives the essential invocation context (no auth, free, session cap, sample questions) and the schema explains defaults, so a basic call is possible. But with no output schema, it never states what the preview actually returns or how the free/quota behavior maps to the paid query siblings.

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?

Schema coverage is 100%: slug and question are fully described, including defaults and echo behavior. The description adds no parameter detail, but none is needed because the schema carries the burden.

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 identifies a concrete resource ('pmnews: Prediction-Market News Index') and frames the tool as a free preview with sample questions, so an agent can tell it is a taste-of-listing tool rather than a generic action. It stops short of a crisp operational statement like 'returns public metadata for a listing', relying instead on promotional language.

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?

It clearly establishes when to call: no API key needed, free, and 'call this now', which distinguishes it from the paid/session-based data_session_* siblings. It does not explicitly name those alternatives or state when not to use it, so it lacks full routing guidance.

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