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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety and external-source profile is covered. The description adds that results are 'ranked' completions and optionally localized, which is modest context beyond the structured data; it says nothing about return shape or rate behavior, but the output schema and annotations carry that burden.

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 tight sentences with the core purpose front-loaded and the sibling routing second. Every clause is doing work; only minor room to trim the locale phrasing that the schema already covers.

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 an output schema present, return values need not be explained, and readOnly/openWorld annotations cover the safety profile. Purpose, source differentiation, and localization are all addressed, leaving only minor gaps such as fallback behavior for unsupported locales (which the schema already notes).

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 all three parameters (q, count, locale) are already documented in the schema, including the ll_CC form and clamping. The description restates the prefix and ll_CC locale concepts but adds no syntax or format detail beyond the schema, so the baseline 3 applies.

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 (Fetch) and resource (Qwant's ranked search-box completions) with clear scope (for a query prefix). It explicitly names the sibling tools google_suggest and bing_suggest, so an agent can distinguish it from other autocomplete sources without opening a 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 second sentence names alternatives (google_suggest, bing_suggest) and the comparison intent, giving clear context for when this source is relevant. It stops short of an explicit when-not rule (e.g. that this is Qwant-specific and shouldn't be used for general web search), so it isn't a full 5.

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