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

Annotations already declare readOnlyHint and idempotentHint, and the description does not contradict them. It adds useful behavioral context about cross-service, all-at-once search behavior that goes beyond the structured annotations, though it does not describe return format or result limits.

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, both necessary. The core function is front-loaded, and the usage guidance plus alternative routing is delivered in the second sentence without 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?

For a search tool with a simple schema and full schema coverage, the description is largely complete. The only slight gap is that it lists news, video, markets, and posts but not social or reminder, even though "everything" suggests full coverage.

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 baseline is 3. The description reinforces the free-form cross-service nature of the query but does not add meaningful parameter-level detail beyond what the input schema already provides.

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 description uses a specific verb and resource: "Search everything this instance has collected, across news, video, markets and posts at once." It clearly distinguishes itself from narrower siblings like news_search, and the scope is immediately understandable.

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 description explicitly states when to use this tool: "Use it when the question crosses a service, or when you do not know which service would hold the answer." It also names an alternative and the condition for choosing it: "news_search is narrower and better when you know it is news."

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