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

Annotations already establish read-only, idempotent, closed-world behavior, so the bar is lower; the description adds genuinely useful operational context — no API key required, 0.01 USDC/query, max 20 queries per session — which is behavior an agent can't get from the schema or annotations.

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?

It is padded with marketing repetition — 'No API key needed' and 'FREE preview — no key, no payment' say the same thing twice — plus a price line and sample questions, while the actual purpose is buried mid-sentence.

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?

With no output schema, the description should say what a preview actually returns (metadata only? one sample answer?), and it should position the tool against the many data_session_* siblings. It does neither, leaving an agent unable to predict results.

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% and both parameters (slug, question) are fully documented in the schema, so the baseline applies; the description adds nothing about how slug routes or that question is merely echoed back.

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 mostly advertises a listing ('rustsecwatch: RustSec Crate Security Advisories') and says 'FREE preview', but never states the verb clearly beyond 'preview' — it does not explain that this returns public metadata/sample answers about a paid data listing, nor does it distinguish it from sibling data_session_query.

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 urges 'Try one of the sample questions now' but gives no when-to-use vs. when-not guidance, no mention of when an agent should graduate from this preview to data_session_open/data_session_query, and no prerequisites.

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