Ask across the right sources

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

Annotations cover safety (readOnly/openWorld/non-destructive), but the description adds substantial operational context the annotations do not: up to five engines selected, automatic time-window inference from phrases like 'this week', a cap of 10 results, and a concrete cost of 5 credits. Cost and result-cap disclosure is exactly the kind of trait an agent needs for budget-aware selection.

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?

Three tight sentences, front-loaded with the trigger condition, then capability and cost, then the routing alternative. No filler and nothing repeated.

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?

An output schema exists, so return values need no explanation, yet the description still usefully bounds the result count. For a single-parameter discovery tool, the trigger condition, alternatives, cost, and result cap together make it fully sufficient to call correctly.

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 coverage is 100% and already documents the query parameter, including platform and time hints. The description reinforces the time-hint inference mechanism ('infers a time window from phrases such as "this week"'), adding a little meaning beyond the schema, though most detail is duplicative of the schema text.

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 concrete verb and resource ('describe what you are looking for in natural language') and frames the scope as cross-source discovery. It explicitly contrasts with the sibling 'search' by naming the condition that separates them, so an agent can distinguish the two without opening schemas.

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?

Gives an explicit when-to-use ('when you do not know which source to search') and an explicit alternative with its own condition ('use search when you already know the engine'). Both sides of the routing decision are stated.

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