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

Annotations already declare readOnly=true, idempotent=true, destructive=false and openWorld=true, so the safety profile is covered. The description adds a genuinely useful behavioral nuance beyond the annotations: it discloses that the budget may be SHARED with other campaigns, which is exactly the risk an agent needs to know before touching a budget. No error/pagination behavior is described, but for a single-item read that is a minor gap.

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, zero filler, with the returned fields front-loaded and the actionable workflow hint last. Every clause earns its place and nothing could be trimmed without losing information.

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 no output schema, the description correctly compensates by enumerating the returned fields (status, channel type, daily budget, shared-budget flag). Its only real omission is parameter documentation for the two required IDs, which is meaningful but not fatal for a simple two-parameter read tool whose annotations already establish safety.

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 0% for two required parameters, so the description must carry the burden of explaining campaign_id and customer_id. It only implies a single-campaign lookup via 'for one campaign' and says nothing about identifier formats, where the IDs come from, or account scoping. This leaves the agent to infer parameter meaning from the schema names alone.

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 names the specific resource (one campaign) and enumerates what is returned: current status, channel type, daily budget, and whether the budget is shared. It is clearly a read operation, distinguishable from the sibling setters (ads_set_campaign_budget, ads_set_campaign_status), though it does not name them explicitly.

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?

'Check this before proposing a budget change' gives an explicit when-to-use condition tied to a concrete workflow step (the sibling budget tool). There is no when-not guidance or statement about what to do for a multi-campaign read, but the positive guidance is clear and actionable.

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