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

Annotations already declare readOnlyHint and openWorldHint. The description adds useful context beyond that: it discloses the underlying source ('Bing's HTML suggestion list') and what rich mode surfaces (entity cards with name, description, image, only where Bing shows them). It does not mention rate limits or result caps, but those are covered in the schema.

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 sentences, front-loaded with the core behavior, then the usage note and the rich variant. No filler.

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 a full output schema and 100% parameter coverage, the description need not explain return values or parameters. It covers purpose and the key behavioral variant, leaving only minor gaps like pagination or count limits, which the schema addresses.

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 the schema already documents Query, Rich, Count, Country, and Language. The description's mention of rich=true is redundant with the Rich parameter's own description. Baseline 3 is appropriate when the schema carries the parameter 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?

States a specific verb and resource: returns Bing autosuggest query completions for a prefix. This is clearly distinguishable from the sibling bing_search, bing_images, bing_news, and bing_videos tools, which each target a different result type.

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?

Explicitly names a use case ('Use for keyword ideas') and explains the rich=true variant for entity cards. It gives clear context for when to enable rich, but does not state when not to use this tool or name a preferred alternative.

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