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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds substantial extra context: the exact returned counts, the exclusion of cluster membership, the $0.01 toll quote, and the explicit absence of an x402 payment challenge. It also names the HTTP equivalent endpoint for agents that prefer raw HTTP.

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?

Front-loaded with 'FREE preflight' and the return-field enumeration, which is what an agent needs first. Slightly dense with the em-dash clause and the HTTP equivalent tacked on, but every sentence carries information.

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?

There is no output schema, so the description usefully enumerates the return fields and states what is omitted, which covers the output side well. However, with three undocumented parameters it leaves the input side entirely unexplained, which is a real gap for a tool the agent is told to call freely.

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?

All three parameters (q, days, limit) have 0% schema description coverage, so the description is the only place semantics could be supplied — but it says nothing about the query string, the default 7-day window with a 31-day cap, or the limit range. 'articles_in_window' hints that a time window exists but gives no usable guidance.

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 ('preflight for gdelt_news_clusters') and immediately enumerates exactly what is returned (articles_in_window, multi_outlet_story_count, singleton_count, servable/reason_class, toll quote) and what is not (no cluster membership or representatives). An agent can distinguish it from the paid gdelt_news_clusters sibling without opening the schema.

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?

The word 'preflight' plus the explicit '$0.01 toll quote' and 'no payment required: call directly without payment' make it clear this is the free cost-check step before the paid clusters tool. It does not explicitly state when NOT to use it or differentiate from the same-family preflights (gdelt_news_crypto_preflight, gdelt_news_enriched_preflight), so it stops short of a 5.

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