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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds genuinely useful operational context beyond that: no auth key required, a per-query price for the underlying listing, and a session cap of max 20 queries. These auth/cost/rate-limit details are the kind of value structured fields don't provide.

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 text repeats the same message three times ('No API key needed', 'FREE preview — no key, no payment', 'call this now'/'Try...now'), which bloats a two-parameter tool. Embedding a specific listing slug and price in a generic tool description is noise rather than earned content.

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 simple zero-required-param read-only tool with full schema coverage and no output schema, most needs are met. However, the description interleaves a listing price ('0.01 USDC/query') with 'FREE' claims, leaving the actual cost of THIS call ambiguous — a meaningful completeness gap for a capability meant to be called without payment.

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 description coverage is 100%, so both 'slug' and 'question' are fully documented in the schema itself. The description adds only a loose allusion to the question parameter via sample questions and clarifies nothing about slug resolution. Baseline 3 is appropriate when the schema carries parameter semantics.

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 title and copy convey a 'free preview of a data listing,' but the description is dominated by listing-specific sales text ('scinewsmag: Science News Magazine Articles') rather than a clean verb+resource statement. It never distinguishes itself from the sibling data_session_query, so an agent must infer the boundary. The clearer scope statement actually lives in the schema description ('guest-callable taste of a listing'), not the tool description.

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 implies usage with 'No API key needed — call this now' and 'FREE preview,' suggesting this is the zero-friction entry point before paid queries. However, it never explicitly contrasts with data_session_query or discover_agents, nor states when NOT to use it. Usage is only implied through urgency phrasing.

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