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

The description discloses key behaviors: debiting budget, activating campaign, and handling insufficient balance by returning shortfall info instead of an error. Annotations only indicate mutability (readOnlyHint=false); the description adds valuable detail about side effects and error handling. It does not address idempotency or multiple calls, but overall is sufficiently transparent.

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 with no redundancy. The first sentence states the core action, the second adds important error behavior. Every word earns its place, and it is appropriately front-loaded.

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?

Given the tool's simplicity (1 param, no output schema, minimal annotations), the description covers the main behavioral aspects: action, source, prerequisite (approved), effect, and error handling. It omits permission requirements or return format, but those are not critical given the context.

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?

With 100% schema description coverage, the baseline is 3. The schema already documents adRequestId as 'Unique identifier (UUID) of the approved ad request to fund'. The tool description does not add further semantic insight, nor does it need to.

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 clearly specifies the action ('Fund an approved ad request'), the resource ('ad request'), the source ('organization wallet'), and the effect ('debits the budget amount and activates the campaign'). It distinguishes from sibling tools like create, update, pause, or delete ad request.

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 implies the tool should be used for approved ad requests, but does not explicitly state when to use it versus alternatives like submit_ad_request or update_ad_request. No guidance on prerequisites or exclusions is provided, though the sibling set is large.

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