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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds genuinely useful context beyond that: results come from public Bing HTML/async pages and a 503 is returned when Bing serves a challenge page or unusable HTML, which prepares the agent for a distinct failure mode.

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?

Purpose and scope are front-loaded, followed by locale and failure-mode notes. The mid-sentence restatement of the Query and Count parameters is redundant given the 100% schema coverage, but overall it stays compact and readable.

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 the description covers locale defaults, the 503 failure mode, and routing to bing_search. What remains thin is the absence of guidance on pagination/total-result behavior, but nothing critical to correct invocation is missing.

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 all five parameters including their defaults and clamps. The description restates Query and Count and notes the locale defaults (country=us, lang=en-us), adding only marginal value over the structured fields.

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 normalized Bing image search results for a query string') and explicitly differentiates from the sibling web-search tool by naming bing_search. An agent can tell this apart from bing_search, bing_news, and bing_videos without inspecting any 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?

Names the alternative explicitly ('Use bing_search to search Bing web results'), giving a clear routing condition toward web results instead of images. It lacks an explicit statement of when image results are preferred over the news/video siblings, so it falls short of the full when/when-not treatment.

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